I feel your pain bro. I have, or had serious dandruff problem as well. I am 18, but since I was like maybe 14, I have had dandruff problems as well. My hair would itch like crazy when I played sports and sweated. Anyways, the way I cured this is by rubbing in lime juice from a lime, not the lime juice that comes in a bottle. Rub it in your head real good. It should burn, but don't worry. Then after you rub it in, wait at least 30 minutes. Repeat this daily, or every other day, and you should see results. Also, use "selsun blue" dandruff shampoo with it.. Hope this helps bro.
By the way, take a shower after 30 minutes. Lol.