These are all only guesses. There can be so many reasons. If this continues, or maybe even right now, the best thing for the OP to do is to have some blood work done and get a proper diagnosis.
It can range from being something simple, or something deadly.
He is young, so it is probably a relatively minor issue, but you never know.
It can range from being something simple, or something deadly.
He is young, so it is probably a relatively minor issue, but you never know.