Infected anal glands?

My dog went to the vet 3 weeks ago for chronic GI issues. His blood work returned normal, his Texas GI panel was normal, negative Addisons diagnosis, and no findings in ultrasound.

He was put on prescription kibble (Hills Biome) and has tremendously improved since then. However, we are still using his old kibble and new kibble since he seems to get tired of the new one, about (half and half). So far his poops are normal and no further diarrhea/vomit. His appetite is even up.

As of this morning he was a little restless and had a hard time sitting down. He licked his tail a bit but not to an excess. He is still eating well and very happy.

BUT now I’m worried… I saw a little puss come from his anus. No blood and his anal glands do not appear to be swollen nor does he have an abscess. The only thing I can see is the top of his butt is a little swollen. He yelped when I removed what appeared to be a little grass on his butt. I just put hot compress on it and he let me. He has his tail tucked in as well.

I cannot take him to the vet till Wednesday and he is a reactive boy. If this is an infected anal gland, wouldn’t I see a swollen gland or anything further? Since nothing appears to be ruptured, would it be possible to treat with antibiotics and releasing the glands? I know one cannot be certain without visually inspecting but this guy has been sedated a couple of times this last month and hate to do it again and again.

He is 91lb, Labrador/Pyrenees mix, and intact. Thought I’d mention, his stool sample is normal and urinalysis are also normal.