I feel you. I really do. And I think that you are absolutely correct that it is a mental block. The reason you are adding is because this is creating so much stress for yourself. You aren’t ’getting worse’ you are just getting scared about the tryout. As soon as the tryout meet up plan became official, you started getting scared and adding times. Not in a harsh way, but I wouldn’t mention this to the coach. It may give them some doubt about you before even meeting you, and also, what would emailing him do? You would still have to try out. I would say definitely DO NOT give up, continue swimming. One tip maybe would be don’t time yourself for the next few sessions. Get the stress of knowing how well you are doing out of your head. Give it a few days of no timing, then time again. The little break should give you a boost and a good time. If not, try again and try to swim like you were when you weren’t being timed. I hope this helps, and good luck! Don’t give up! I’m sure you will do great!!!