hard lump on forehead

I'm 12 and I've had this huge lump thats almost my whole forehead i got the lump when i was 6 my cousins and i were playing hide and seek in the house i was running out of the laundry room and he was running in the laundry room but we both bumped heads On the wayhe was taller than me at the time so all he had was a bloody a eyebrow and had to get stitches thats when i got the lump and now it hasn't gone since people see the outline now its hard for me to talk to people without them noticing by the way lump has been hard like its grown to be part of my skull