Eh, sorry to start a new thread, didn't want to make people wade through my over-large text detailing her history... Just wanted to give and update on her progress for anyone who's possibly got a lamb in similar straits, was wondering about it, or may have similar problems in future.... I'm assuming she's the only Damara lamb on this site so if they need the particulars they should be able to find her history easily enough.
Re: the sewerage breath: lessened, almost entirely gone. What changed was I fed her as much raw garlic as she would eat. And I've started her on regular activated charcoal treats mixed with yoghurt and other goodies.
Re: the blocked/stop-starting breathing & high-pitched straining semi-audible breathing noises she's been making at night: Gone! (Yay, what a relief, I was concerned about that).
Re: the burping: was gone for a few weeks, came back for a little while, gone again, hoping it stays away.
I'm sure in future some experienced soul's going to have a name for what her symptoms were. Till then...
Oh, and she on and off has problems with her bladder control, particularly peeing frequently, and sometimes peeing while laying down. I've got no idea what that is but am almost completely sure she had pulpy kidney when she was younger. So possibly a bit of lasting damage.