You need to do some obedience training with her, and with your son. Keep her on a leash, and keep her focussed on you. As soon as she starts following him, tug the leash, and tell her "sit" and make her wait a minute. Does he ever do any walking with her? He should learn to walk her on the leash, so she gets used to him being in charge. Is he involved with feeding her, or giving her treats?

Also, yes, her hormones kicking in may have to do with it. Are you going to get her spayed after her heat is over? That will certainly help calm down.