Dandruff problem. And also applying oil!

I've been having dandruff for a long time now,it started out with white spots but now it had turned into yellowish flakes, when I scratch my head it felt like there was whole layer of dandruff, plus at times, when I scratched my head the scalp used to be moist and yellow flakes of dandruff was falling out, I shaved my head two days ago, so I could treat this dandruff problem, but even after a thorough head wash with head and shoulders shampoo, when I wiped my head with a towel, there was dandruff on my head again, please tell me what I should do, I really want to get rid of my dandruff before my hair grows out as I won't get a chance to shave my head again. As home remedy, I'm currently washing my head with besan powder and also applying oil