Work work work work work work

Ok ladies I need some advice. I’m an assistant groomer.. Very fast paced, stressful environment, long hours. My boss knows I’m pregnant, and if she pays attention she would notice how I haven’t been feeling good. I’ve worked through it all week, even with the holiday chaos. Today I had to draw the line and call of to take care of myself. I’m exhausted. I have never felt so emotional, exhausted, nauseas in my life. OH AND MY BOOBs. At work I’m constantly bent over a tub lifting bad and big dogs up, on my knees up and down I just couldn’t deal today. She can’t handle call offs because there isn’t anyone that could do it like me. I understand that and it took everything for me to call off. If you can’t tell I’m a very guilty feeling person, I fear disappoint and I just want people to be happy. Anyway. She replied by saying “today isn’t the best day to call off. I have to cancel so many dogs now”. As if I don’t feel bad enough.. I do so much for her and this company as least I thought... idk if I’m looking for reassurance? Advice? Your stories?? Really anything.