Never had this weird rash before

Hey everyone. So I have this weird rash on my stomach and underarm, I have recently started using tampons again and I accidentally left one in for 9 hours over night 2 nights ago (I usually wake up to pee and change it but I was too exhausted), not sure if its tss. I also had thrush recently, completed my week course of micreme cream on Friday. I also stopped taking birth control for the first time in 10 years 35 days ago. I know this isnt a medical professional but just thought I'd ask if anyone else has had the same thing? Just thought I'd ask before I spend $100 at the doctors incase it is normal