Sick Small poops and air bubbles?

This is the only thing I could really find: https://www.guinealynx.info/forums/viewtopic.php?t=9157

I'd strongly recommend taking him to a vet. Guinea pigs can go downhill very quickly, and mucousy-poops don't sound good at all to me.

Heavens! No vegetable oil -- you didn't read that on this forum, or if you did, it was posted by someone who didn't know what they were talking about. Constipation isn't usually a problem with guinea pigs unless they've been on pain medication, and it's surely not the first thing I'd think about with the symptoms you described.

First, does his stomach feel tight, or sound hollow if you thump on it gently? If so, he probably has bloat, and that's a medical emergency requiring a visit with an exotic vet as soon as you can get there. You can read (broken link removed) for tips on what to do until you can get him to a vet.

If those aren't his symptoms, I'd separate him for a little while, either into one end of the cage, or into a laundry basket or other confined area, and put him on a light-colored towel or piece of fleece. Feed him hay and pellets, and make sure he has water. Watch to see if he's pooping, and what the poops look like. If he is eating and pooping, then leave him there for a few hours and see if the poops improve. No veggies.

But, you should know that a pig sitting still either doesn't feel well, or is in pain. They're often hunched up, or fluffed up, if they're in pain. If that's the case, he also needs a vet quickly.

Are you weighing him regularly? A failure to thrive, or a loss of weight, is often the first sign that a pig is ill. You should be weighing both your pigs at least weekly, and daily if you think something is wrong. If you think he isn't getting enough to eat, take him out of the cage a couple of times a day and give him some extra food.

Right, I would make a vet appointment. The mucus and small poops signify a gastrointestinal problem. I wouldn't necessarily separate them totally--can you use grids to divide the cage so they can still be near each other and see each other? And then you could monitor his food intake and poops. Has he lost weight?

Thanks, I did read it on here about the veg oil, I just found it again
https://www.guineapigcages.com/forum/about-guinea-pigs/8705-constipated-piggy.html

He's not lost any weight. He doesn't sound hollow, or have a tight tummy. It wasn't mucus, but resembled it until I inspected it further, that's when I discovered it was a bubble (of air, I presume) I'll get an appointment with the vet as soon as I can