My scalp all of a sudden began burning & it hurts when i scratch. a smallump on my neck popped out of nowhere as well.could this be due to the heat?

See a doctor: You need to see a doctor for a history and physical. These symptoms could be due to an infection, which could cause lymph nodes in the neck to enlarge in response, helping to fight it. An infection will need treatment, and there are other possibilities as well, that need to be considered - hence the visit to the doctor.

Likely Infection: It is more likely due to an infected area of the scalp. The lump is a lymph node draining the infection and not due to the heat.