Thanks for the additional information. Well, I took everything you said into account- your age, your previous surgery, your medications and the description of the pain.
Unfortunately, there are a number of possibilities for this, some of which could be concerning. In specific, this could be an inflammation or infection of the colon, called diverticulitis (diagnosed by CT scan and treated by antibiotics), kidney stone (diagnosed by CT scan and treated with hydration and pain meds), bowel obstruction
(diagnosed by CT scan and treated with either decompression with a nasogastric tube and hydration or sometimes surgery) or gas. Now this can certainly be gas pains. However, if you presented to my ER, I would do a complete blood panel on you- including complete blood count, chemistries, urinalysis. As well, I would do an xray of your abdomen- this can tell me if you have a bowel obstruction (a large one). But if you are feeling better with some fluids and some pain meds, I would send you home to follow up with your doctor in 24 hours for a recheck. However, if you did not feel any better or if you had any lab abnormalities indicating infection, I would get a CT scan. To be honest, this is gettting worse and not better and is happening more frequently. I would see your doctor first thing in the am. If you cannot see your doctor, then you need to go to the ER. Of course, if you get any worse tonight, you should go to the ER right away.