Gini - I don't know if you know this but Momma will go right back into heat when her babies are about 6 weeks old. Now I didn't know this - I was in a similar situation when I finally could get close to my stray Panda Bear. By the time I could get close to her she was pregnant and subsequently delivered 3 babies. When she bolted out of my house about 6 weeks later, she came back and the back of her neck was all wet so I knew some male had had his way with her. So I called the vet and that's when I was informed about her going back into heat. She was spayed very soon after and indeed she had been inpregnated again.