I strongly recommend switching to a holistic diet (not Royal Canin-that's a "emergency brand" for when you can't find the good stuff, IMHO). I'm convinced that the stuff that's allowed in commercial foods causes loads of problems (see post #4 here:
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=243x2281#2294 ), including vomiting, diarrhea, gassiness, weight gain, dandruff, behavioral problems and even severe illness. I know that a holistic diet cured my elderly cat Miro of the same problems you've described, and many of my friends who have switched to human grade foods have had the same positive experiences. www.waggintails.com and National Pet pharmacy are good places to go for holistic brands. Try Spot's Stew, Wellness, California Natural, Merrick, Newman's Own or Innova for wet food. Organix is the highest quality dry food I know of, but Wellness and Artemis Fresh Mix also make fairly good dry diets. My Oberon prefers dry food, but all three get wet food twice a day, in very moderate quantities (so nothing is wasted and they don't overeat). I also feed Kosher pets freeze dried beef diet and Brother's Blend raw diet for variety. There's lots to chose from. Try going to www.artemiscompany.com and use their search feature to find a retailer near you if you prefer not to shop via the internet.
On Edit: Here's a short list of some holistic pet food retailers in your state. A larger health food store will probably also carry some good brands:
NaturesRules, Inc
PO Box 413
Stokesdale, NC 27357
(800) 431-9266
(336) 427-2526
(336) 427-8784 faxRetail Stores
Asheville Pet Supply
1451 Merrimon Av
Asheville, NC 28804
(828) 252-2054
Phydeaux
103 West Weaver St
Carrboro, NC 27510
(919) 960-3606