If she's responding to pressure between her toes, sounds like a foot problem.
If unsure, I'd ask the vet to look at her, as any illness is likely to affect her ability to lamb herself, and the health of the lambs, and her health at this time, illness or problems that may put them off eating such as sore feet/legs while pregnant can be fatal.
You haven't said you have given her painkiller, but you have said she's in pain.
I would think you need someone experienced in sheep, preferably your vet, to look at her feet and treat any foot problems, and if the vet sees her, they can examine her all over and treat any other problems detected appropriately, but sounds like she will at least need some pain relief.
If she is choosing to lie down rather than walk around much, you could make things worse by trying to assist her with slings etc. I'd focus on addressing the pain and the reasons for it and she should then choose to walk by herself without assistance.
Let us know how you get on.
Ps I'm not sure if you have company with her, but sheep often can get distressed, making any health problems worse, if removed from the flock, so maybe you could make sure she has a friend to keep her keen while you look after her in the "hospital wing".