It really helps to know your texture and porosity to give advice. Here's a thread to help with that: Texture, Porosity, and other Hair Type Madness

It could be build up, the change of weather, not enough protein, too much protein or any of a lot of other reasons.

My salon has the Deva products, when they changed the NoPoo ingredients about 18 months ago, it really dried out my hair. I won't let them use it anymore. Don't know how frequently you use the mousse. My stylist feels that the propellant in mousse is drying and advices against it. The AnGel has a polyquat fairly high on the list. I can't use them. They build up on me and cause spider frizz.

You don't use a lot of moisturizing products--at least to my hair, so that could be it, too.
3a (Corkicelli), highlighted, fine, low porosity
modified CG, since April '07
CG since 3/11/08

SE PA

HGs: Anything Sevi; Curly Kinks Satin Roots, Curlycue ReNew and Coil Jam; homemade FSG and okra gel; soap bars; UFD Curly Magic (now Hello Curly Curl Stimulater); Botanical Spirits Jellies, CJ Repair Me, Marie Dean Leave Ins and Curl Creams