hey Mystic, stomach cramping or the feeling that you need to eat to settle you stomache sounds more like a side effect of taking a more potent opiate. All opiates call your bowels to slow down and cause constipation, this is from a diect effect on the bowels, The sensation of hunger is the way your brain responds to whats happening in your stomach, like cramping or grumbling or nausea. There are some stomach meds that won't interere with abosrption of short acting meds but you still want to satay away from meds that coat the stomach whcih prevents absorption. Zantac or pepcid or something prescribed may calm your stomach if it becomes a bigger issue.
For now I would just say be aware of what you eat. There is no reason you should have to gain unwanted weight because you need something to settle your stomach. If you take it with milk or food, it's less likely to cause those sensation or you can use something like baked Rits if your weight or calorie conscious. It's really not likely hunger, but more like caused by spasticity that's caused by the more potent drug in an empty stomach.d that like getting goosed with a rod as your walking through a stoor, it stops you in your tracks.

Opiates effect the entire GI system, from your stomach untill they leave. They aren't known to cause a false sense of hunger in your brain.
JMO
Good luck, Dave