Any ideas on firming up a loose stool in a cat? he is 2 yrs old. been treated for tape and round worms.?

at the shelter he was treated for worms, ringworm, fleas, and earmites. he acts fine. the poop is like lons of pudding, and i am used to seeing cats make "tootsie rolls" if you know what i mean! problem is that he steps in it as he turns in his cat box to cover it up...i have been feeding eagle brand dry food..hairball formula. with a tblsp of friskies wet in am and pm. when i stopped the wet it didnt make a difference. i just bouth science diet i/d (intestinal formula) on the advice of a friend. i will take him in to the vet again, but i wanted to try some home remedies first. he has been throughly checked recently and had no health issues. also i tried giving him a probiotic in his food for 2 weeks...no better. any ideas??