We had a ewe la,b triplets and the third lamb's hind leg was problematic - couldn't weight bear and buckled forward at the hock. Vet had a look and said it was probably how the lamb was lying in the womb - there was a name for it. Anyway, within a day the leg was growing stronger and in 3/4 days he was walking normally. No problems now. Hope yours will also come good. I think I offered a bottle top up for the first couple of days and also helped him into suck at the ewe. Good luck!