So how fast does he eat his food when you do give it to him?
I feed Frosty half home made casserole and half kibble. If she's eating too fast, I put the kibble in a treat ball so she can't eat it so quickly.
Also if Rocky is a ridgeback - isn't that one of the big breeds and you feed for slowing the growth? Ie not puppy food?
What are you feeding him? brand/variety dry kibble or soft?
I had problems with Frosty getting the runs every couple of weeks for a few days, was driving me nuts and making the local vets wealthy. Fasting her then feeding boiled skinless chicken and rice for a day was very inconvenient. I switched dog food from Advance Puppy to Nutro Natural Choice (the upmarket version of Advance), and she hasn't had the runs since. Well not unless she gets into the compost or silage - which was once. Not even the worming tablet made her get runny poo now. Now, she's over 12 months old, so I've switched again to the adult nutro natural choice and it's all good so far.
Some dog owners have to go through a very careful elimination diet to find out what food is ok for their dogs to eat and what isn't. Hope whatever the problem is - is just a matter of finding the right food for you.