WHY:
As EFT founder Gary Craig puts is, tapping with EFT is a bit like clearing a forest. You find many things in a forest, in all sizes and shapes.
Weeds: these are small inconveniences in our life. One example could be a child having lost a toy, but then finding it back very fast, so it was a brief enough fear. It could be a flat tire a day when you had time and all you needed to get it fixed. It was annoying, but it was easy enough to fix. No big concern. Just step on it!  
Brambles and prickly shrubs: these are bigger annoyances, we might not see the roots of them, but they sure are prickly. They grow insidiously, duplicate themselves and have a tendency to take over if we don´t watch them. Let´s say Noel let a glass of water fell when he was 6 years old. Aunt Rosie commented on Noel´s clumsiness. For many children, that really wouldn't matter. It wasn't even said in a mean way. But Noel happens to be a bit over sensitive that day because his cat died. The comment is quickly forgotten by all involved, but every time Noel sees somebody who reminds him event remotely of his aunt, every time a child lets a glass spill, every time he hears a slightly derogative comment, he has this slightly uncomfortable feeling. It doesn't really matter, but it grows slowly in some form of mild anxiety. This anxiety feeds on other events that life throws at him. And one day it becomes a bigger anxiety. Again, this how Noel reacted. His pal Kurt would not have been touched at all by the comment.
Or take Marguerite´s story. She´s taller than other people. At school, other kids used this against her, and everywhere she went, she felt out of place. Her size is an hindrance to her. So much so that every cell in her body tries to get her shorter. She´s literally carrying it on , or even IN her back, and develops an arthritic pain. A very prickly shrubs indeed.
Small to large trees: They range from the single frail birch, to the solidly grounded, strong oak, or these poplars colonies where what appears to be dozens of trees, dozens of trunks, is actually one single root system, one single being (some of these colonies have been estimated to be 80,000 years old. How's that for longevity?!. More on wikipedia if you´re interested!en.wikipedia.org/ wiki/Aspen). Back to our comparison, these might range from what happened to Noel, in different circumstances when he took it so badly that he remained strongly insecure in every move he does, every word he says (check up Soairse´s case study for a similar case), to more ¨obvious¨ traumas, such as the death of a loved one, abuse, either sexual or not, a divorce, a car accident....

SO?
When we start tapping, we are literally tapping into our subconscious mind, where all of our history is stored, with its associated memories. Even when we don´t identify the source immediately, the feelings start coming up. And sometimes it can be overwhelming.
Remember though that EFT does NOT CREATE emotions, but it digs them out so you can deal with them and free yourself from them.

WHAT CAN I DO ABOUT IT?
Well, depending on your personality and preferences, there are many ways to get through this. Take EFT as a Swiss knife. You can use it in many different ways.

Technique 1 - Head first:
You might be willing to get through this as fast as possible, no matter the intensity. You pick the first strong event you can think of. Again depending on your personality, you might want to get ready for an emotional roller coaster, and then again, it might go very smoothly. Experience will tell, we're all different. Feelings might get very strong. For some people, it´s instant, and so is the relief. For others, it takes longer, and you might feel it in your day to day life for a while. Some people might even feel a kind of a physical ¨detox reaction¨, with body aches, that then evaporate. These can be tapped away of course. The difference with the side effects of medication, is that it does not leave long term damage anywhere, on the contrary, every small reaction is an opportunity to tap away a few brambles or weeds. One word of caution, if you are facing a big trauma, I would advise you to seek support when you tap, either from a trusted friend or from a trusted practitioner. Whatever you do, remember you are taking full responsibility for your own well-being.  

Technique 2 - Beating around the bush, so to speak:
You don´t want to get through this roller coaster, this is scary,  you can´t deal with so much. Then take a slower road. Start looking at minor hindrances and tap them away. With time, you'll build your strength and your skills on how to use EFT in your OWN way. Then one day, you will either be ready to face ¨the big one¨, or you´ll realise that the generalisation effect worked for you : you tapped so many brambles and bushes away, that the big tree in the middle had no more protection and just collapsed on its own.

Technique 3 - Building up:
Even beating around the bush might be too much for you. Then you can take an even softer route. Start rebuilding your strength and positivity. Use the Gratitude round, the positive tapping script, tap with ho´oponopono whenever something happens. Tap away minor annoyances as they show up. Physical pains are a good target as well. In time, you will feel safer and stronger enough to get to the aspens and the oaks of your forest.

And in all cases, if you feel you're not making the progress you expect on your own, get some support from a qualified practitioner. 

Did this help? Any comment or question are welcome.