Job discrimination

So I’m just stressed right now... my job requires 16 hour days, which I manage getting thru them bc it’s only 2.5 days out of the week. Yay, my 40 hours is done.. but my doctor just put me on a restriction to not work OVER 16 hours per day. Sometimes my job requires you to work and awake 24 hour shift. Yes you heard that right. So today I got called into the office, 4 days after I handed them my restriction note and they tell me that I can no longer have my job bc I can’t perform the duty of working over a 16 hour day. I don’t have ANY trouble completing my job, it’s just the “forced overtime” they make you pick up. They offered me a different position, however I would lose my sick and vacation benefit hours and if I can’t pick up more than 30 hours then I would lose my insurance too. What the eff!!! Is this legal? Isn’t it discriminating the fact that I’m pregnant. I’m so sick over this because I need my job, I need my insurance, I don’t need this added stress. And they told me to figure out what I want to do before Wednesday, this Wednesday!! Help. What do you ladies think about this??