As the other responces indicate, a UTI is usually accompanied by severe pain, an inability to hold in urine, pain with urination, adn someitmes fever and other flu-like symptoms. So it is probably not a ITU. BUT it sounds like he is dehydrated if he is peeing so little. Give him water, juice, milk, popcycles, sports drinks, bascially whatever he will drink (of course plain water is best, but to get him interested in drinking more "fun" options can be more sucessful). Buy him his own water bottle and encourage him to drink from it when he is playing outside. And take him to the bathroom even if he says he doesn't need to go. I would sometimes give small treats or stickers to my kids just for trying. I have heard that putting some Cheerios in the toilet for aiming practice can be a fun way to get little boys to pee in the potty, I have only potty trained girls so I haven't done that one yet! Good luck!