I have a ewe with a ruptured tendon, as well. I first noticed it and I was like "WOW! She's huge! I bet there's triplets!"
As days went on, I realized that her "baby bump" was on her left side and I knew that wasn't quite right. Googled it for more info, came up with this diagnosis.
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She ended up having twins, ram/ewe. The ram was first, and I believe first born (or died shortly thereafter). I got to the barn and I saw her in labor with the ewe. I had to help her deliver the ewe. I couldn't get any milk out of my ewe (despite her succesfully having lambs in 2014/2015) and so her surviving ewe lamb became a bottle baby.
This is what my ewe looks like now:
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She gets around okay, I almost wonder if something else was going on with your ewe? Our vet said she should be okay as long as she's not bred again. I've never seen her stiff as you had described your ewe. Since I've moved from my parent's, I am letting her stay there with my first ewe (she was born in 2006) and a few others that aren't really the kind of sheep I want to continue to produce, but they're too much of pets or I have sentimental reasons to keep them, lol. The more production-oriented/proven sheep are coming with me to my new house.