pain after exercise

Bex

I'm 9 weeks post partum after a catagory 2 emergency c-section and last night I did a small exercise routine (15 Squats, 30 Seconds Arm Circles, 1 Minute Wallsit, 15 Wall Push Ups, 50 Jumping Jacks, 30 kettlebell [6kg] swings, 10 Crunches) I had breaks and water and felt fine afterwards but when I woke up this morning my stomach skin is killing me it feels like uts burning and tearing and some of my stretch marks look like new ones all pink instead of faded brown like the others. why did this happen?