For what its worth, my son produced upwards of 14 nappies a day full of sweet smelling goo/mucous poo prior to being diagnosed with lots of food allergies, even to milk and wheat etc coming through in my in breast milk! It seems that if yucky poos are not accompanied by dreadful pain, blood, severe skin trouble then you're probably ok and he'll grow out of it once his gut gets used to grown up foods. You might want to reduce fruit juice, oats etc as they tend to be er cleansing! However, the other thing is whether the poo is greasy and greyish as this can really be a sign of malabsorption/ coeliac type problems... have you shown your GP a fresh sample?!! Way to go methinks! good luck!
( by the way, even if allergies/ intolerances are diagnosed, there's a lot you can do with even a limited diet, believe me!)