Why would a bump appear on your forehead when you have not banged your head?

If u have been angry or very stressed out lately that's what it is probably from. u should probably see a doctor and get a prescritption just to see if its not too serious! I'm not sure, but, It has happened to me. One on my forehead, then my index finger, now the back of my head......Stress may be a factor, but, I'm heading to the doc tomorrow...