It is difficult to diagnose without having a look on all skin problems. It can be allergic reaction to food, contact allergy or side effect of any medicine. Another possibility is insect bite or bacteria or fungal infection. For temporary relief apply hydrocortisone cream and take anti allergy medicine and the visit to doctor for proper diagnosis and treatment.
Could be anything from contact dermatitis to shingles it does sound like it could be ringworm tho... You should check with your doctor for proper diagnosis and treatment, however there is bluestar ointment available OTC for ringworm!
If you are a man and you starch, or the cleaners starch, your pants....it can cause the small bumps you are talking about. If you wear a belt around your waist, and cinch it a little bit tightly, you could be causing ingrown hairs. You could try scrubbing that area ( entire body, actually), with a loofah sponge or a japanese wash cloth. For those of you who don't know what a Japanese wash cloth is, it's only one of the greatest inventions ever. You can get them at drug stores or bath and body shops. They are about a yard long, a foot wide, with a texture perfect for soaping up and scrubbing off dead cells, and opening ingrown hairs, and other stuff like that. I don't even feel clean if I shower without it now; that is how much I love it. You can also sling it over your back like a sweater, take it in both hands and pull back and forth to scrub your own back. They are perfect for people with back acne, and the overall removal and exfoliation of dead skin cells.