Tummy difficulties are common side effects of withdrawal. The good news is it will resolve itself in a few days, weeks. While you are having trouble in one area, your healing process has started in another area, like the lungs.
If you are taking prescribed drugs like Chantix and Zyban, these are known to contribute to discomfort. Usually, when people quit, they tend to eat more due to the hand-to-mouth habit from smoking, which adds to the misery.
The best way to deal with it is to start exercising the regime. This Will combat the tummy side effects and regulate your body. Drink lots of water. I also took raw honey, which is known to have lung healing properties.
From Chain-Smoker to Non-Smoker 