A.S.
Can you tell if he's doing it as he urinates? It's possible he could have a urinary track infection. This is the very same sign I had that something was wrong with our almost 2 year old daughter had a urinary track infection. You should probably take him to see his pediatrician just in case. In the mean time, offer him cranberry juice to drink, I water it down 1/2 and 1/2 juice/water. Our pediatrician also recommended sitz baths. Warm water, up to their waste, dissolve 1/2 cup salt in the water and 1/2 vinegar. Kind of agitate the water a little with your hands while he's in there. (This worked for our daughter, but I'm really not sure how it works with little boys.)