May be constipation or just trapped gas. Maybe try some Gas-X after meals.
Not the same as your situation but if that continues, you may want to check with your doctor. Years ago I had an ovarian cyst rupture and had severe rectal spasms. Not sure if your issues might be causing the pain
Take magnesium citrate every morning. Add Metamucil pills (5) with a big glass of water. If this is not effective, switch to Miralax powder in water. Eat an apple or pear every day and chew thoroughly. Glycerin suppositories can get things started. Use a probiotic every day. Glutamine powder assists digestion. Sometimes improving blood flow is needed. L-arginine and maca can help.
Sounds like you may still be constipated or perhaps have a partial blockage?
Have you tried a stool softener? If you keep getting pains on left side, which is where your colon is, and you are unable to go and cant pass gas, go to ER right away. Just suggesting this from experience. Best wishes.