sudden hair loss

Hello, I have had sudden hair loss for about three months now. It first started in the temple areas of my head but now it has spread to the the crown back of my head and to my sideburns. My head itches all of the time and I have noticed that when I touch my head it is very sore and tender around the crown of my head and also in spots where i have experience some hair loss. I have also noticed that when I examine hair that falls out of my scalp some of the hairs have really big white or tannish bulbs on the ends of them. I have even went to my dermatologist for this problem and he perscribed me some medications for seboherric dermatitis, but the itching and soreness is still reoccuring. My hair loss is also starting to get worse as I notice when i rub my hair and I notice at least 10 strands of hair comes out at one time. Also, i don't know if this has any meaning but outside of the general itching and soreness I sometimes get shooting itching pains and sensation of something crawling in my scalp (sometimes). And i have notice small bumps (some of them pus-filled) in the temple areas of my scalp where I have experienced hair loss. Please Help,

Thank You, Eric