My 20-year-old son is 5ft 8in tall and weighs 130lbs. and has had problems with kidney stones in the past, but is otherwise in excellent physical condition. He now has blood in his urine, and is starting to feel some pressure similar to previous episodes of kidney stones. I know he drinks to many soft drinks and has not been as good as he should about following the doctors advice about other things avoid. I know that he smokes marijuana, but he denies other drug use. Is it possible that smoking marijuana could lead to blood in the urine, or make it worse?