We had Billy on JWB since he was 3 months old, then all of a sudden his poos became loose. i thought he just had a tummy upset but this went on for about 4 weeks, exactly the same as you describe. this happened when he hit 6 months. He was fine in himself so i knew he wasnt feeling poorly. Every now and then he would wipe his bottom on the floor! :? :? :? :?
Our trainer told us to watch his protein levels as he had so much energy and was becoming a real real handful. Apparently too much protein aint good. When i looked at JWB it was 30% protein. We were told to try a diet which was much lower in protein.
A few weeks ago i decided to change him to Burns, 21% protein, (although he is still as energetic as he was on JWB) at the time i just thought it was the only thing i could do.
I did it gradually, mixed a bit at a time with his JWB, i introduced the food over 10 days, now he is on 100% burns.
I must say that since i have changed his food his poo is absolutley fine!
and back to normal. It may just be coincidence but i doubt it.
He does not pooh as often either. On JWB it could be 5-15 times a day but now itis no more that 4 times usually. Burns said apparently it is because the products are natural and therefore contain less ingredients which are not required by the dog and therefore less waste.
If he does not improve its worth a try.