My 12 year old boykin spaniel has started randomly falling over. Its like her back legs give out and she falls down, then gets right back up. She doesn't limp or anything, she just falls down.

Should I be worried?

My parents don't think its a big deal, and we don't have that much money. But, I just got a job and I get my first paycheck on the 24th. Ill end up paying for it if I take her to the vet. Do you think waiting until the 24 will be ok (if she is still doing it then)