My 18 y/o male turkish angora has soft stool

He's been healthy most of his life; last vet check the doc was impressed by his age and his health. Lately he has been having soft stool, not diarrhea, but not much shape either. He's in dry k/d (happy to say his kidneys are in very good condition according to the doc). Wet food he's been having the whole foods brand (365) oceanfish tuna formula, some times sheba different flavors. He demands (you know they never ask, they demand) his wet food in the morning and in the afternoon. Sometimes I boil some chicken liver, I used to gave him raw chicken liver, but then he started to throw up, not nice to clean... yuck! I don't know what to do to help with his stool, I can't afford a vet at the moment, so hopefully somebody will be able to help me.

Congratulations on his relatively good health!  Is he on K/D because he does have kidney disease, or what? 

Have you recently changed anything (added the 365 food, or done anything different, maybe started adding water to his canned food, anything like that?  Changed flavors of food?

Do you give him probiotics?  Assuming you answer "no" to all my question, then I might recommend a good probiotic for him.  I, personally, give my cats a human probiotic, although there is currently a discussion among the team members that debates that.  I know there are lots of members here who feed human probiotics, and several of us use this one:  http://www.thecatsite.com/products/natural-factors-double-strength-acidophilus-bifidus-10-billion  I give my furkids approx 1/3 capsule with each meal (they eat 3 time per day). 

Here is a link to some reviews on probiotics.  Scroll down the page to find Natural Factors, Mercola, Eagle Holistic, Purina FortiFlora and Jarrow.  http://www.thecatsite.com/products/category/vitamins-supplements?sort=rating 

If you answered "yes" to any of the above questions, that could be the issue.  Change can sometimes equal disgestive issues   Let us know and we may be able to provide more input.