I was holding my ball python today, and saw that from his vent and three inches up the skin is a dark blue color, right at the vent there is something hard and white. He hasn't gone to the bathroom in a while, and he normally goes about once a week (its been almost two). The skin is very tight were it is blue and is very sensitive... I took a pic but you can't see anything... Anyone have a clue what this could be? Or, any advice what to do.?