Hello,
For these bumps, frictional lichenoid dermatitis and granuloma annulare should be ruled out. Granuloma annulare is a chronic disease consisting of a rash with reddish bumps arranged in a circle or ring. Usually it is asymptomatic but due to cosmetic disfigurement topical or oral steroids may be needed.
I suggest you to get it examined and discuss this possibility with a dermatologist.
I hope it helps. Take care and regards.