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 of retained hair spicules in the scalp left over from he transplant. These spicules are a foreign body so your immune system isolates them, and they pushes them out. If you only have a few once in a while as you said, it is best treated with warn soaks which will push out the foreigh body as these pustules are induced to ‘pop’ or dain spontaneously. This problem rarely occurs after the first 3 months following a hair transplant.