“Pain on one side and gas.”

Hi there, since a few days ago my stomach is a bit bigger than usual and I have gas. I started to feel like that after one of bowel movement. Yesterday I noticed part of my stool in lighter color than the rest and I was having cramps before the bowel movements. Today the cramps are gone but now I have a slight pain the upper right side of my body, like by the ribs and I had some nausea earlier but now I feel better and my apetite is back. I notice I feel like this from time to time. They did an ultrasound for my abdomen back in 2018 all clear and my last complete bloodwork was in september and all good. I suffer from constipation since I was very young and anxiety and I do spend a lot of hours sitting down due to my job. I also had a colonoscopy in 2016 all clear and stool test in september 2022 was negative. What could this be? Thank you for your help!