ho boy, I've had the knee aches and muscle aches and the plantars. I still have to stretch my Achilles tendons every day (I do it in the shower, ha, several times for each leg). doc wanted to give me an orthodic, which at the time I first had the problem (boy, was that excruciatingly painful) was too expensive for me, I had no insurance either. instead I used good, cushioned tennies, and still do.
http://en.wikipedia.org/wiki/Plantar_fasciitis
hang in there, and don't let it bum you out. it's definitely something you can take care of (I agree that you should get the diagnosis confirmed)