There's a couple of things this could be, especially given age. Unfortunately, most if not all should end up with a vet visit.
1st: Onset of Arthritis. Fairly self explanatory.
2: Some form of nerve damage/disorder, at the simplest a pinched nerve. If this was the case I'd have your checked for osteoporosis.
3: Slipped disk.
4: Oncoming neurological event (stroke).
5: Muscular (at the simplest, a pull).
you get the idea. Unfortunately, the growling could be due to pain, fear, or personality change from stroke. The raised tail position... could apply to any. I'm sure I'm leaving out possibilities, but I'm trying to stay simple!)
3 of these are treated with simple steroidal and the like. The others, it depends on occurrence and severity.
Which, in the end, means you should probably have kitty checked out.
Thank you so much for the information, I will keep an eye on her. If it is a stroke, is there other signs I should look for? Thank you again for responding. I've been freaking out. I will get her to a vet ASAP.
The only really obvious sign of stroke in a cat that's telling is an abrupt personality change. And that's assuming your cat isn't in pain and just p-offed because of that. Otherwise, short of seizures (which you haven't seen yet, but can start after a stroke), there's no way to be sure in the short term without testing. Good luck, and glad to help!