scalp issue- dandruff or buildup?

Hello,

I am having an unbearable time trying to figure out if this mess on top of my head is dandruff or product buildup. A stylist said it was product buildup but no other stylists have mentioned it being that to me. She said it could be because I'm using cheap products...well I am not. I use Joico K-pak reconstruct shampoo and conditioner. On other days, I use Ouidad Curl Quencher Moisturizing Shampoo and conditioner. Once every 2 weeks, I use Paul Mitchell clarifying shampoo three. Once every week, I use Matrix Essentials solutionist Instacure leave in conditioner and macadamia oil. Even when I just shampoo/condition and cut out everything else, I still get a crusty scalp. The flakes are large, pure white, and caked onto my scalp. Please help me discover what the problem is so that I may begin using the correct method to get rid of it. Thanks!!