maybe...cancer or hepatis a,b,c.you should immediatley get checked out!
ANSWER
cancer can not make yoru head tender or your hair fall put, please don't worry about that
allergy, dermatitis, eczema of the scalp can all cause these symptoms
you may have a skin condition, so go to a dermatologist first and rule that out
also brushing it too much will give you dandruff and loosen the roots.