I have this problem too.
I've swapped cows milk for soya
Cut out bread
Eat an activia yoghurt every day
Drink more water
It could be:
*a food intolerance
*slow digestion- so longer time for fermentation
*could be an indicator that you are thirsty
*early warning that you are hungry
I have this problem, i don't know what it is, but it's not always that im hungry, because it rumbles even after a big meal, but it might be because when i swallow, talk and eat i swallow to much air, and it makes it rumble, that i know happens, i tried swalowing air to see if it was that, and it worked, but i'm afraid i don't know what to do about it.