Now and then i get really bad tummy ache and rumbles. I don't think it's hunger... (read description)?

…because i sill get it even if i eat tons! (However, eating seems to stop it.) And it’s not period pains.

It’s not frequent
Occurs at around 3:00pm on school days
I’d say i eat a balanced diet. Shreddies for breakfast; apple for brunch; bread, 2 apples, and a sharon fruit for lunch; sometimes a packet of polos when i’m walking home; then poultry and veg for tea.
I reckon i have a flatulence problem- holding them in at school… that surely can’t do much good.
If i don’t eat, my tongue goes into a spasm (or feels really odd) and there’s tons fluid in my mouth. It’s really painful.

Also, no matter how much food i cram in, my stomach is always rumbling in class at around 3 also. (and same if i don’t eat so much)

So, any ideas? Or is it just freakishly extreme hunger?