stress rash or bugs? :/

I can’t tell what’s going on with my skin. I tried asking before on Y!A about this, I thought it might had been a spider bite and now I just don’t know. For almost a week now, everytime I wake up I find a red blotch on some part of my body. it usually has a small bump and is very red around the area and itchy. But it shows up in the most random spots. Before you say bed bugs, these are large red bumps and are not close together unlike how bed bugs are. My mattress is brand new as well and all my bedding was washed 2 weeks ago (which I make a point to wash every month to every month and a half) the blotches start going away after a day to 2 days. I showed two of my friends the marks and they both said it looks like a spider bite. I have searched my room and house high and low and I can’t find ANY bugs what soever. I even tried looking to see if there are bed bugs with a magnifying glass, nothin. bed is clean as ever, so I have no idea what is going on with my skin. My mom said maybe it’s a skin rash, but dont rashes stay in the same area? I keep getting these in random places. Like one is on my left arm and another is on my right ankle to my right under arm and my left thumb. :/ what is going on? I have to wait till monday to see my doctor he’s been out for a while so I really would like to try to find answers even before then