It might be because the opiates slow down the digestive process and now that you aren't taking as much or hardly any all, you body is probably either digesting food more rapidly or trying to get back to normal.
I am not a great person to ask as I just started c/t today and the withdraw is screwing with everything!
It is very common and will last for a few days. I only have gone c/t for 3 days and my stomach sounded like the Gulf of Mexico. Congrats on day 3!!!
Always,
M