Help - found a lump at the back of my head. What is it?

I was brushing my hair and caught something on my scalp - pulled the head of it by accident and whatever it was was like a greasy abrasion, it healed quickly and I didn't worry. Now the area around it is very sore, like a bruise, going down my scalp a bit further I have found a small bump/lump which is painful like a bruise to touch. Does anyone know what it could be? Quite worried. Also, if I am not touching it I can feel it aching. Someone help me please! I plan to go to the doctors as soon as I can get an appointment but until then, if anyone has any helpful information on what this could be I would be very thankful.