Little update. I've been over at guinea lynx since a member there had the same symptoms that I'm having. The exotic vet's advice was surgery on a severely underweight guinea pig and then chemo to clear it out. She didn't think the thyroid medication would work because it was looking too much like cancer.
I took him to my vet, who does exotics as well, but he's a mix of that and cats and dogs, but I figured, why not. He retested T4 and that was it. He said he didn't want me to go through anymore or the little guy, as he calls him. T4 came back negative, but I'm finding there is no accurate reading for this. And he said the only way to tell if the lump was indeed cancerous was to do a biopsy. He said there was no accurate way to tell unless that was done, but he refused to do the surgery due to his weight. And I agreed.
Long story short, he fell to 684, and is now between 653-672. His eating is insane, and he's always hungry, and has now been on tapozole (banana flavor, they didn't have carrot) for a week today. I hope it works, but seeing how he's still here and still functioning, I'm going to take it as a plus.
He started to wheek again today, which I haven't heard since the lump appeared. I took that as a good sign. He's currently in a playpen to separate him from his 1300 brother, who can be a bit rough, but I do put them back together during the day to make sure they're not apart all the time.
(Hope photo isn't too large, feel free to edit)
