Painful ache

Hope

9 weeks postpartum...I have this huge ache between my stomach and ribs...and it comes and goes it’s VERY painful...and aches for 5-10 minutes. And goes away.... it feels like constant flexing and soreness...yet I am relaxed. I am not constipated etc...when I get the pain it’s sometimes hard on my stomach like im flexing but I’m not... when it comes you can’t ignore it, stops you in your tracks. And when it happens my back begins to hurt as well