Ooops forgot to also say that if you add 1 tablespoon of 100% PURE canned pumpkin to his food it will help solidify his poop. Make sure it is pure pumpkin though (NOT pie filling .... it has loads of sugar). Usually if my guys need their anal glands cleared out I add pumpkin. Or if they have diaherria I feed them boiled chicken breasts with white rice and pumpkin. Firms it right up!
Or if they are constipated they get ..... yup you guessed it PUMPKIN! Its fiber and will regular them.
But it does sound like there is something else going on. So yes a vet is in order