I know I shouldn't bail on her, but I don't feel like taking care of my sick girlfriend
That's pretty inconsiderate. Is there any special reason why you can't take care of her?
She took care of me back then when I was sick, but now that the tables are turned, she is asking way too much. Sorry sweetie.
If she is contagious then I assume you don't want to catch it, but for other reasons I have some doubts. Take care of her and tell her that you can only do so much. You will be too stressed out and get sick yourself by being over worked.
Fine, I will take care of her just to keep our relationship functioning.
I'm glad you've decided to step up. Just make sure to take precautions in order to stay well yourself.