Answer: Digestion, stomach flu, gallstones or IBS
Step-by-step explanation:
This could many things. Gallstones would be one of the first things to check for, it is a common problem and once the stones become large, they cause problems such as the ones you have described.
A stomach flu, also known as a bug or food poisoning is also likely and so is IBS.
if the problem did persist, more serious issues could be investigated if everything else is rules out. Such as pancreas problems.