Ok so looking at this methodically, (you're welcome, and I have issues with dry itchy scalp so I can relate to the frustration) it seems that the white flakes and itchiness appeared after you used the aloe vera juice? Have you ever used it before? Do you have dry skin on any other parts of your body or your face? Are you allergic to garlic, onions, hyacinths, lilies or tulips? (they are all in the same plant family as aloe, Liliacea.) Aloe juice is a much more concentrated form than aloe vera gel, so you might need to dilute it some next time. That's a possibility. The last thing I would say is, if you only water washed, you may have not massaged or scrubbed your scalp enough to get the sebum and dead skin cells off (wasn't that why you did the oil/sugar scrub in the first place?). Overall, it sounds to me more like a skin issue, not product buildup.
2a/b, high porosity, fine strands, average density, just about shoulder blade length

My hair loves moisture!

currently mod-cg , using low-poo and not totally cone-free yet. I'll get there though!