Perhaps your son has allergies to foods
with acids? Both
orange juice and spicy foods have lots of acid content. You could trial him out on the over the counter Zantac, which is an H2 blocker, and will help with allergic reactions as well as indigestion. Or his own production of gastric acids are in excess and with the added acids in those foods, it leads to sweats, like when people eat hot chilli or hot wings.