Asking for work leave?

Angela

I'm at a loss right now, I work as a waitress fulltime an a cna part time. It's so much physically to handle. My back hurts like hell when I get off nd my legs hurt so bad and back that I can barely walk after I get off. How do I go about asking my dr for a note to go on work leave or bed rest due to it physically draining me and hurting me??

EDIT I'm 30 weeks