Certainly could be stomach gas. Have you been to the doctor? Do you have any other gastro symptoms like acid in your throat, nausea, cough, heartburn? Are you lactose intolerant? Does this happen when you eat or drink certain foods or at certain times of the day or night? Are you wearing super tight jeans like my 19 year old does?
You could try some Mylanta, Phazyme, or GasX, but if it's been going on for three months, I'd have a doc take a look. He or she can give you a correct diagnosis and get you fixed right up.:) Many hugs:)