Every time I have Phys Ed I get teased and the teacher rolls their eyes and my face goes red I can't stand it! What can I do?

Speak to the teacher personally and tell him that his behavior is causing you grief. If that does not work, then speak to the principal.

This sort of behavior by a teacher is not tolerated in many school districts. It does not matter whether the course is PhysEd or Math... the teacher should not publicly humiliate a student - unless the student is clearly acting out of line.

I managed to get out of phys ed by taking extra courses. Talk to the guidance counselor, the principal, any one you can. Even when teachers are told to stop treating students the way this one is, the other students can be merciless, and the more the teacher tells them to stop the more they tease afterwards. So I sympathize.
Your ID says you are nerdy. Smart nerdy? Be proud of it. These days nerds have a lot of cachet if they play their cards right.

First remember not everyone is a at sports, in fact only a small group is actually good, some fair and some really bad, It does not mean you don't need the exercise and does not mean you should not try. Are some kids bad at math, some bad at english, thus some bad at sports.

If the teacher is making fun of you, tell your parents and hopefully they will go see the school to have a talk with the teacher. It is not your place to talk to the teacher, it is your parents. And hopefully they will support you.