I think I understand the point of kata now, it’s supposed to kind of get you into the feeling and movement of things and one shouldn’t give out full force while trying to memorize it to preserve energy and to not tire yourself out without reason, I think.I can't speak to any medical issues, but I'd wager that the OP is trying to hard to be "tough," or "angry." I saw a youth at a karate demo doing a kata (and yelling "kee-ai!"), but he was so tense, I could see that Y-shaped blood vessel on his forehead quite easily. Very bad.
It's unfortunate that we need to learn how to relax, when we shouldn't have been tense in the first place!
So, OP, just put your limbs where they need to be. Don't try to be tough. Relax. Doing this stuff while tense is like driving with your foot on the brake all the time. It prevents you from moving easily and smoothly.