J.T.
the biggie that comes to mind is diabetes. chances are it's "nothing", but i'd really cut down the sugar intake(most yogurts have more sugar per serving than ice cream!). fruit is high in sugars as well. has he lost or gained a significant amount of weight lately? if you can get him in sooner, run him in, they'll probably just check his urine for glucose, tell you all is well, and you'll rest easier! good luck!