I can't really tell, from the picture. What greens does he eat? I'd transition away from any high-calcium ones, like carrot tops & toward low-calcium ones like romaine.
He actually hasn't eaten much greens the last couple of days as I haven't been to the store and there isn't much growing yet. In the winter he eats store bought spring mix. In the summer he eats dandelion leaves, chichory, clover, thistle, carrot tops, plaintain, etc. We are kinda in transition from store bought to fresh picked. This has been the routine since he was a baby.
Here are two more pics fwiw. The smaller "dribble" spot on the one pic is what makes me think theres a bladder issue.