just gotta throw this out there..today i actually knocked my 4 year old off his feet (with my belly)because he walked into my belly.I'm 30 wks.it was so hard not to laugh as i picked him up off the ground.so if your bumping stuff now better be very careful it only gets bigger..luckily it didn't hurt me and we are both having a talk about making room for mommy wen walking/running around.
It sounds like a tough day, but remember that it could be much worse. There are many moms that work on their feet all day, etc. As long as you're not lifting above the weight designated by your doctor (at that point for me, it was 40 lbs), you should be fine. I used to waitress and had friends there that were pregnant- constantly running around to their tables, carrying trays (of drinks, not food generally), and more, and they did that up until delivery. If you want to leave, make sure whatever you're going to will actually be better for you than what you're leaving.