when will I learn?

last night David took Maddie for a nice long walk. she came back so energized and puppy-ish. i haven't seen her that revved up in a while. she started running circles around downstairs on the hardwood floor. she was skidding around and playing her game of "chase me" that she hasn't played in sooooo long. I, like the over grown dumb kid I am, started chasing her and laughing. It was so wonderful to see her like the old days. Chris kept saying "be careful, she's an old woman" but I was enjoying myself. Then she ran into the living room and let out a yelp. when I got to her she was stumbling around with her hind leg up and to the side. picture a male dog getting ready to pee. she limped around for the rest of the night sometimes walking on it, sometimes lifting. of course I cried and felt terrible. gave her some pup aspirin. today she is limping and moving slowly but not complaining at all. so I'm torn. take her to the vet or wait it out. I can't stand seeing her limping but the vet always wants to run every test known to man (or vet) and we just can't afford it. She looks so sad. ugh! guess I'll watch her for a bit and then decide.