Ugh! I'm so sorry! I've never had it, but from everything I've heard, it's agonizing.
It really does suck. I was worried it was a hairline fracture in my heel or something until I looked up plantar fasciitis. Then I was 99% sure it was that. The worst is after you are off it for a while and stand up, it's all tight and I can barely walk on that foot.
Also it kills after a few hours standing on it, especially while umpiring. And I'm umpiring about 10 hours straight on Sunday.