Is it a sweat gland or hair follicle? Those can present as bumps under the foreskin. Does it itch or is painful? Then it might be an infection but otherwise is probably simple irritation. There is something called pearly penile papules. Are your lumps anything like this describes. https://emedicine.medscape.com/article/1058826-overview. Best thing to do is see a doctor as they can probably give you a quick diagnosis. But I don't think I'd be overly worried.