Singulair and herbal medicine

Okay- A friend just emailed this site to me, my son is 4 and has been taking Singulair for about 2 years. He has seasonal allergies which seem to be year round, asthma and food allergies. He is on Singulair and Allegra daily, this in it self freaks me out. What I have noticed for at least the past year is that when he is running around or moving a lot he hold his right side and says he has a pain in it, we now call it a "stitch". it happens not from strenuous activity, our doctor just says its growing pains, that doesn't make sense. something is bothering him it happens with somewhat frequency. I am really thinking about his behavior, it seems to me he can change on a dime. from happy to very angry, outbursts and then right back to sweet, yes this could describe any 4 year old, but not any 4 year old is on Singulair. I remember saying to him where is my sweet boy? I feel like that might have been when we started the meds, i am so used to his behavior now that it seems almost normal but there was a time he acted differently. and i do remember saying that.... was it when he went on Singulair???