How does everyone cope with working whilst dealing with symptoms?

I currently work as a part time sales assistant but at the end of the month I'll have a new full time job in a school whilst still working in the shop. Ill be working six days a week, me and my partner want to work as much as we can for the little one and to move house before the birth. Currently I'm suffering from cramps, nausea and a UTI. I hope and pray my symptoms subside before I start my new job because it would look really bad if I'm off for sickness or not able to perform well in my role as a teaching assistant. How do you ladies cope? Do you just suck it up and get on with it? Did you have to have time off? And how understanding are your bosses?