No, but it's not too late to make sure they don't get overfed while pregnant, resulting in bigger lambs and possibly even narrowing of the birth canal, compounding the issue.
With older Texel type ewes going to a Texel tup, many farmers wouldn't cake much while pregnant if possible, to avoid the overlarge lambs issue. But depending on where you are, it can be a challenge to keep the ewe from getting twin lamb disease and to also have enough input to ensure a good milk supply.
It's even more tricky with hoggs, who are still growing and so must be fed sufficiently while pregnant.
If at all possible, it is very much worth getting the ewes scanned, and probably not feeding any carrying singles, or you could well end up with very large lambs that are a struggle to get out.
But back to your original question, ruminants can't actually vomit at all, so it sounds to me as though it's that she's ejecting food she can't swallow. Possibly because it's too dry, or the nuts are too big to swallow but competition at the trough means she's trying to wolf down as much as she can as fast as she can.
When using sugar beet shreds, we always soak them thoroughly in at least the same volume of water, and for several hours, be they for ruminants or equines. (They will swell to more than twice the size at some point, and inside the rumen or gut if a greedy sheep or horse has eaten too many of them can cause bloat / impaction, with disastrous consequences. So I prefer they do their swelling up before ingestion.) Then mix the soaked shreds with the hard feed before putting it in the trough, so that the whole feed is moist, which will help with the swallowing. And ensure there is plenty of room at the trough so that all the sheep can eat at the same time without the bully sheep hogging it all. (Which usually means two or three times the length of trough that you think you should need! Or as you say, spread it out in a long line on the grass, but again, making sure every sheep can eat at the same time, without being bullied off.)