What Causes Feeling Of Lower Abdominal Pain While Standing?

Hello, My 14 year old son is Autistic, He eats onions like apples and I don t know if that is why he is having this problem, but within the last 15 minutes he says he has a pain in his lower left side and it comes and goes, my son says it goes away when he is sitting but, when he stands he can feel the pain, is this due to his rocking cause of his Autism or because of the onions and my child says the pain isn t that bad, but then he has told me he has been wearing tight pants, could you please help me, he s not feverish and he says the pain is gone when he doesn t stand or move around. Thank you for answering my Question. Donna