It sounds like build up. It seems you've only been using the products that work for you for a couple of months at most - I assume you found them after the sulfate mistake (I've done that, too, lol). Try clarifying - a simple BS wash should work for that. Also, are you living in a new location since school started? The water could be different. Hard water can cause problems.
remember, with all advice or suggestions for your hair, YMMV!!
My hair:
2b wavy, medium texture, low porosity, med-high density. Protein finicky.
My routine:
Cleansing: DCNP, every 4-5 days (occasionally use CJ cleansers).
RO: CJSC, occasionally use JCDC
Gel: KCCC, CJCIAB for 2nd day hair (sometimes third)

Heat is my friend: warm water rinses, steam caps, and diffuse dry. I love CLU cloths and my Denman.