What Causes Scarred Tissue In The Brain?

I've been hearing voices and seeing strange shadows since I was a little girl...would I have some sort of mental problem? I'm 17 years old and weigh 106 lbs.I'm 5''1 and I suffer from bad asthma and allergies.As for any other medical issues,I do have scarred tissue in my brain.I was born with it,but doctors were not able to figure out why since I never sustained any injuries when my mother was pregnant with me.