Feels like pulling muscles with bm

Pain is likely from rectal inflammation or muscle spasming. A few questions to narrow it down.

1.) Does the pain exist before, during, and/or persist after the poop is over? Inflammation-based pain is often limited to during the poop, continued healing over time with a focus on rectals (steriod or mesalamine enemas) help clear it up. Spasms tend to be in all three aforementioned categories and are often treated with anti-spasmatics like bentyl.
2.) Is the painful poop more formed, more dense, or larger in diameter than your normal is? Rectal inflammation can lead to what I call razor-blade-poops. You're healed higher up meaning the poops are getting formed, but your rectum still has severe inflammation and is very narrow in inside diameter, so passing those feels like crapping out razor blades or broken glass shards.