Bumps on my head as well as scalp, since past 4 weeks, they are temporary and not painful, reduces in sige after few days, casuse? Treatment?

Gonna need more info. Questions like your are important ones to get an answer for, but your description just isn't enough for many doctors to reply with a safe, reasonable answer. I'd recommend seeing your doctor in person and have it looked at - since a picture is worth a thousand words...