Getting taken out of work?

I have been having dizzy spells and falling for about a week now, my OB sent me to the hospital Friday to get checked out but they sent me home after doing a non stress test and blood work. Ive worked one day since then and because I work in retail, its chaotic and I don't have time to sit in my department, which has obviously caused issues with me already being dizzy and I've fallen a couple of times too. It happens at home as well. I'll be 30 weeks on Thursday and at this point I'm worried its only going to get worse and I'll injure myself or my baby. I see one of the OBs at my office tomorrow and I was considering seeing if they'll pull me out of work early. My employer has ignored previous notes from my doctor about accommodations, like the lifting restriction I have, and have so far refused to move me to cashier or somewhere i could actually sit during my shift or let me have breaks to sit down. I already know how the disability and maternity leave works in my state and with my company so I'm not asking about that. I just don't know how to explain this all to my OB and bring up being taken out of work. TIA.