Hello,
I cannot confirm anything without examnation but it can be intertrigo,heat rash or contact dermatitis.An intertrigo is an inflammation (rash) of the body folds.It most commonly occurs due to bacterial,viral or fungal infection. An intertrigo usually appears red and raw-looking, and may also itch, ooze, and be sore.
Pls keep the area clean and apply some topical antiseptics. Also wear loose-fitting cotton clothing and use an antibacterial soap or mild soap like dove.Avoid any kind of cosmetics.Topical zinc oxide cream like Sudocrem, Desitin are very helpful(apply with a paper towel and not directly with hands).Application of mild steroid cream like dermacort also helps.For the itching pls take some over the counter antihistaminic like benadryl or Claritin.In case the symptoms persist then antifungals may be needed.Pls consult a dermatologist in that case.
Hope it helps.Take care and pls do keep me posted in case you have any additional doubts.Kind regards.
You might need a more potent cream. If the rash is primarily on your inner thighs and has a border. Then it is probably jock itch. You need to dry off the area well, with a clean towel. Apply the cream twice a day for at least two weeks, even if it starts to get better. But you can stop thinking about it being an STD. Its not.
Don't use a wet towel and always dry that area before your feet.