I've had plantar fasciitis for more than 20 years now. I have a (very old) web page with some information about the condition. Not all the links work now, but most do and some of the info is still useful, especially a link about taping, which can be very helpful for a very bad flare-up.
http://bugsbest.com/plantar.htm I haven't updated the site in years, and for some reason the formatting has gone wacky, so try to overlook all that.
The link to the ProStretch doesn't work anymore, I noticed, and it really did help me. It's an easy way to make sure that you stretch the
right way, which can be hard for people. I'm an old ortho nurse, and I know how important it is to stretch the right muscles. You can find it pretty cheaply online - just do a Google search.
Other than stretching, icing really helped me to get the inflammation down. Know that you have to wear supportive shoes - that means arch supports at all times, either custom or OTC, or Birkenstocks, or even Crocs. Crocs work great for me, but are horrid for other folks. You just have to see what works for you.
If these 'intermediate' measures don't help, then a trip to the Orthopaedist is in order. Steroid shots can make a world of difference! Good luck!!