@MrsWinslow - The thing is that it's kind of a delicate ecosystem down there. The treatment by itself is not dangerous, but if your problem is not yeast but, say, bacterial vaginosis, treating for yeast can put you further away from feeling better by killing off "good" flora as well as yeast.
There are always a variety of different microorganisms - including yeast - in your vagina. When they get out of balance, the result is an infection. For instance, taking antibiotics for some other condition can bring on a yeast infection by killing off both "good" and "bad" bacteria and making room for yeast to grow.
I guess my point is that if you treat for something that is not really the cause of your condition, you can make your condition worse by causing further damage to your own personal ecosystem! It sounds like you are pretty familiar with your own body, though, and in your case you might be able to tell if a particular event was not yeast but something new.