Needing advice

Hey ladies! So I'm 32 weeks pregnant and for the past month I've been having to leave work early for pregnancy related issues. One point it was due to swelling which was caused by being on my feet all day at work (I'm a 2 year old preschool teacher). Then another point I had to call out and go the doctor for what I thought was strep throat but turned out to be a pretty bad sinus infection. I can't catch a break these days. Now recently I've been having dizzy spells and yesterday had to call my doctor at work to ask what they suggested I do and they asked to see me. So I had to leave work early and get my fiancé to take me to my doctors office. While I was there I asked about returning to work and the doctor suggested I stay out the rest of the week (with a work note) to give the medicine he prescribed me a chance to work. He gave me medicine to take as needed for dizziness. I took it yesterday after I got home and laid down but the dizziness is still there. The doctor said it's probably caused by the iron supplement I was on giving me an upset stomach and causing me to have a lot of bowel movements and making me dehydrated. I just feel so bad with leaving work and I feel like I've been letting my coworkers down a lot and I hate having to leave and call out. I just know that pregnancy takes a lot out on the body but I would hate myself if everyone was talking badly about me at work... How has everyone else been doing at work? I'm not sure if it's because it's the first time I've worked 40 hours or if it's because of how strenuous my job is but I've been having a lot of concerning things go on.