Eriathwen
Adult Guinea Pig
we haven't tried metacam for a few weeks, I will suggest this to the vet as a possible next step. after antibiotics and bisolven for almost a week, the 2nd piggie with this issue (it only started a week ago with her, but I never had her last winter when the other one gets the same issue) there is really next to no difference. the first piggie I've given bisolven to as well for a week and it doesn't seem to help either. both are fine in themselves!
interesting about the brachycephalic piggies, I hadn't actually heard of that before. is it obvious? one of mine was from a breeder and I've had her 6-7 years and it's only been since last winter this has been an issue. the 2nd I only got her in June but I don't know her history as she was a neglect case but was an outdoor piggie.
I think we will look further into the dental issues, but there are no signs of abscesses/ underlying infection. so my only thought was if a tooth or root or something was pressing on a sinus or part of the respiratory tract. neither are off their food or appear to struggle eating. both eat long strand hay no problems. having said that, the vet did said piggie 2s teeth are a little sharp and could do with a dental but it's nothing urgent, so I could get that done anyway and see if it makes a difference.
I know what you mean about it bothering yourself more than the pigs. I think that is definitely the case here. I will be exploring more options with the vet but I'm not going to stress too much as they are ok!
It's fairly obvious to be honest, the worst ones nose is quite flat (my vet said she looks like Voldemort from Harry Potter

I would definitely try to rule out dental issues, another thing I forgot to ask is have they been checked for heart issues? That can often cause fluid to build up in the lungs causing noisy breathing.
But as long as they're behaving ok thats the main thing, I know they hide illnesses, but when you live with them you can tell pretty quickly when things are off. Weighing them weekly if you don't already will help pick up any weight loss before most other clinical signs present themselves.