Update
We took Guinness to the vet and had to wait forever to be seen. Ultimate the vet said that Guinness looks good, and her back knees are inflamed, so she does have arthritis. She also has a fever, which the vet said could either be an infection, so she gave us an antibiotic, or it could be caused by the arthritis. Either way, she didn't find anything seriously wrong--her heart and lungs sound good, she's not squirmy or tensing or in pain other than walking. We are having a really bad storm right now and in terms of achey stuff, my foot hurts like crazy. So it's really not that far-fetched. I've kind of suspected Guinness of having arthritis for awhile, I know Shadow had it, and her joints pop a lot. It's just never been this bad before.
The vet already gave her some of the pain and antibiotic meds and she said that the pain meds should take a couple of hours to kick in, then she should be feeling better. I was more scared than anything else that this was a repeat of Shadow's episode. She was breathing heavily last night (though likely it was the fever, and actually the vet said with the storm, she's getting a lot of pets with random infections), and Shadow had real labored breathing at the end. But she seems to be a little more perky even now. We got a thermometer just for her and she's staring at me because she knows what it's for and where it goes...
The vet already gave her some of the pain and antibiotic meds and she said that the pain meds should take a couple of hours to kick in, then she should be feeling better. I was more scared than anything else that this was a repeat of Shadow's episode. She was breathing heavily last night (though likely it was the fever, and actually the vet said with the storm, she's getting a lot of pets with random infections), and Shadow had real labored breathing at the end. But she seems to be a little more perky even now. We got a thermometer just for her and she's staring at me because she knows what it's for and where it goes...