How to get out of swimming in gym class?

I have mandatory swimming in gym in May. I am kinda fat (flabby) and have scars everywhere. As a little kid I would never pass up a dare and I climbed trees allot so I got injured allot. And I always scratched mosquito bites allot. The result is a ton of scars... And I'm a tomboy. We have coed swimming and I really don't want to swim. Or be in a swimming suit in front of the class. What can I do? Thanks!!! And I can't get fit in about one month.