My cats eyes are bloodshot eyes and swollen shut NEED HELP?

I woke up today with my cat comen in the window i started petting her and seen around her eyes are swollen and bloodshot and waterie she still eats and drinks fine.What should i do i hate to see my cat like this.There is a dead snake in the road i dont know if she got bit by the snake somewhere and i cant find it would that have somthing to do with it.PLEASE HELP IM A 15 YEAR OLD BOY TRYING TO HELP MY CAT.