Hello,
These red bumps can be due to contact dermatitis, insect bites, allergies or viral rashes. You need to take antihistaminics like benadryl or Claritin. Longer-acting antihistamines are available by prescription. They cause less drowsiness and can work just as well. These medications include fexofenadine and cetirizine. But they should always be taken under medical supervision. Moreover you may try calamine lotion on the rash. You should also maintain hygiene and try to keep the area clean and dry, wear loose-fitting cotton clothing. Also use an antibacterial soap or mild soap like dove.Avoid deodorant / cosmetics. You can also use a barrier cream with zinc oxide paste or petroleum jelly or a thick moisturizing cream applied directly to wet skin after bathing.
If the rash persists then it will be best to get it evaluated from a dermatologist.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.