A small lump on my head? this is symptom of cancer? i consult a doctor 3 months ago he said " its movable no need to worry" but iam too much afraid

Talk to your doctor : Most likely benign like cyst or similar nature. But if you are concerned them talk to your doctor about taking it out.

Not likely.: It depends on how it might have originated, but essentially i think your doctor is right. If it were a brain tumor, it would have a focal neurological deficit, like headache or seizure, and it gets worse over time. If it were some other tumor, it would likely have other symptoms and signs, and if it was skin cancer you'd likely have a history of sun exposure. If it doesn't heal, see dr. Again.

Has it changed?: Just because it is movable does not mean it is nothing to worry about. However, most lumps have characteristics that tell docs that we need to evaluate it further or not if its not worrisome. Since it has been 3 mos. It can be reevaluated and if it has changed in a worrisome way then it may need further evaluation. At 24yo its unlikely to b a cancer but it could something else in need of tx.