Your picture is either a supranumary teat or a wart, I would need a closer look to be sure which one.
It wasn’t there previously so don’t think it’s an extra teat. Definitely looks possibly like a very small gammy bit to the end. The lambs are definitely coming off in next couple of days so will check her out and have a feel of it, and prob spray with some AB and keep an eye on it.
It’s been suggested it could be a cyst or abscess caused by a blocked gland or lambs teeth I guess, or getting prickled by a thistle or some such. I know our Badgers came back from rough grazing and a couple had some marks to their udder from thistles, though none in a lump like this.
I think the problem with the sheep is they aren’t commercial meaty types and that’s what everyone wants. Plus I don’t want to sell them for less than we paid, especially as they’ve done they’re first lambing now. The guy that sold them to us suggested hanging on to them till Autumn and that there’d prob be more interest as breeding season approaches. I appreciate the year is speeding by. Most people that contacted wanted ewes or lambs, not both together!