Hello,
These red bumps can be due to irritated hair follicles causing folliculitis, sweat dermatitis, heat rash or pityriasis rosea which presents as numerous patches of pink or red oval rash. I suggest you to get an evaluation done from a dermatologist as the treatment is different for all. Till that time, wear cotton clothes and apply some calamine lotion on the bumps.
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.
can this rash go on the legs also