I Have Been Developing These Yellow Bumps on My Head, Every Other Day and Then They Pop and Go Away. (Photo)

After a hair transplant, some people develop these yellow pustules as a reaction to the retained hair spicules in the scalp left over from the transplant.  These spicules are a foreign body, so your immune system isolates them and pushes them out by draining them. If you only have a few once in a while as you said, it is best treated with warm soaks. This will cause the pustules to ‘pop’ open and drain spontaneously.  This problem rarely occurs after the first 3 months following a hair transplant.