1. Are you using a pre-poo? If not, try an oil pre-poo for an hour on your next wash day. If you’ve never tried coconut oil, I would suggest it as it is the only oil with molecules small enough to penetrate the cortex of the hair and restore moisture from within the strand. If coconut oil does not agree with your hair, try EVOO oil instead. I’m suggesting a light oil first as your hair appears fine and something heavier, like EVOO, may weigh it down. You could also try mixing coconut or olive oil with another oil. JBCO, castor, grapeseed, watermelon or jojoba oil may be good options. (Check out this article that was just posted on bglhonline.net about pre-poos!) 
2. Are you using a leave-in conditioner and sealing with an oil or butter? If not, I’d suggest incorporating both into your regimen.
3. What kind of deep conditioner are you using? Is it a moisturizing or protein-based DC? If you are using a protein DC, it’s important to follow it with something moisturizing. Too much protein can be too much of a good thing as it can cause dry and brittle hair. My hair isn’t a fan of protein, so I use henna as a strengthening treatment instead. You may want to try a homemade DC or adding some food items to your current DC. Bananas (I picked up baby food bananas this weekend to try in a DC), honey, olive oil, castor oil, avocados (fruit or oil) are all touted for their conditioning properties and are great used alone, in combo or added to a commercial DC. Search “homemade deep treatments” to find a variety of recipes at your fingertips.
4. You can use Body Art Quality (BAQ) henna over existing chemical color. But, it is imperative that it be BAQ henna or the results could be disastrous. You can also try cassia (so called, “clear” henna), which provides conditioning benefits similar to henna, but without the color. You may want to try this first if you want to preserve your color. The conditioning doesn’t last as long, but cassia only needs to be left on the hair for an hour and there is no dye release, so the process is a lot cleaner (no need for gloves or newspaper) and shorter. 
5. DON’T RELAX IT*!! LOL!  Seriously, if you already have dryness, applying another chemical process on top of color would be the kiss of death! You’d almost definitely end up chopping it all off and starting from scratch! 

(*Seriously, was it that time of the month for all of us last week?!?! LOL!!)

So, what’s the verdict ladies? Chime in! Have you ever had to deal with dryness caused by a color process? Were you able to do “damage control?” If so, spill!