I don't understand how you can brush but not finger comb? Ripping a brush through is really damaging, which then encourages further tangling down the line. Try finger combing when you are in the shower with conditioner all over your head. Or use a detangling comb with two staggered rows of teeth or a 'Tangle Teezer. Be sure to section your hair off carefully to comb and work from the bottom up not the roots down.
Definitely start conditioner only washing, I hate how even sulphate free shampoo makes my hair feel now, dry and tangly and I cannot run my fingers through. Also cut off any really dry and damaged ends/ lengths, these will snarl up with the healthy growth. If not CO-washing consider condition-wash-condition.
Have you had your scalp issue diagnosed? A dry scalp (xerosis) would normally be improved by conditioner only washing, some forms of dermatitis may not if you get build up or use the wrong oils. It's really important to massage plenty and to rinse super thoroughly.