You need to post a picture. It could be scars.

search keratin filaments

This is the picture of the bumps , it's not very obvious in this picture because of the lighting but when i am in the sun they are very obvious. Ignore the bumps at the top right corner , those are whiteheads.

are kreatin filament the same as sebacous filament? if they are, i dont think the bumps are filament.

Some of them look like flat warts to me, though it could be just the lighting.