R-Will

I have been a CNA for almost 2 years, and while I love my job...It can get pretty hectic. I work in a rehab center with a very strict supervisor and the job is REALLY demanding. I am pretty much running back and forth the entire shift and lifting several times. Recently it has gotten hard. I work 2 8 hour shifts and 2 12 hour shifts a week. I found out I was pregnant about a week ago and since then it has went downhill for me. I am having a really rough first trimester. I am nauseous most of the evening which doesn't help that I work 3PM-11PM. The smells make me nauseous as well. I do not want to quit because I have been at my job for a while. My supervisor does not do light duty, as she has taken people off of schedules for having a doctors excuse to be so. Is anyone else in this position and do you have any tips? I am DREADING work tomorrow and I have already changed my schedule twice in the past few months for school so she won't let me again. Help