Hey JAT, I get muscle spasms in the same area, around the ostomy scar. My abdominal muscles in that quadrant tighten up and it's very painful. Fortunately it doesn't last too long. I noticed this after my colectomy when I still had the ostomy. This is not gas pains *though I get those too*. I think they are more likely when I've been using those muscles, but I also think they became less frequent/severe after I was able to strengthen those muscles after surgery.
You have a newborn, so that must have really stressed your abdomen. Great going with getting a new job & a new baby all at the same time. I get that with a job & kids you have about 5 seconds to yourself a day, but have you tried gentle stretching?