Work problems

I have felt so terrible lately. I have HG and have been on at home iv infusion for about two weeks, I've lost 19 pounds. I called in today, I in general feel so weak, lightheaded, and dizzy I just couldn't deal today. I got a call from my manager today saying I needed to come in at 1 cause I had no PTO left, and we're not allowed to take no pay. So I went in (I'm a medical assistant at a very busy, very short staffed office) and it made me feel so much worse trying to run around. I wish I could just quit but I can't. Do I have any options!?