I am not sure what his ailment might be regarding the bumps, but I did come here to say that forcibly retracting the foreskin at a young age (IE; before puberty) is quite unhealthy and may lead to infection and other ailments. The foreskin is a protective measure and should not be disturbed until your son reaches sexual maturity. Cleaning-wise, it is not necessary to completely expose the glans, and I would recommend pulling it far enough back that the top of the glans is exposed to clean it but no further. Retracting the foreskin before maturity, especially in a soapy environment, is not healthy for the glans!
I hope this helps you in caring for your son!
Thank you for your comment. To clarify a bit - My son was going to see a pediatric urologist and have surgery because his foreskin would not retract naturally. His local physician said it would not had been a problem had it not been disturbing his urine stream. As for retracting the foreskin my son did it all on is own while in the bathtub. He was only two years old so I do not think he knew what he was doing. There is now no problem retracting the skin. As for the skin not retracting until maturity, I can say that his doctor said the natural retraction can happen at any age. It is not medically harmful for the foreskin to retract before maturity and often happens. For more information please review this site - http://www.circumstitions.com/AAP-care.html
I would hate to think someone might read this and heed your advice about reading the above article,
The foreskin may not fully retract in some males until the end of puberty. In some boys this age is 20+ years. If it still does not retract after the end of puberty, then steroid creams can be prescribed. Circumcision is NOT the recommended treatment.
Expecting a 2 1/2 year old to be retractable is not realistic. If the boy is retracting himself it is fine, but it is not ok for others to touch it or force it to retract.
The bumps you describe are "pearly penile papules" scientifically referred to as hirsuties papillaris genitalis. They are nothing to worry about. Google away.