Plantar Fasciitis is a nasty inflammation of the tough tissue or tendon that runs along the bottom of the foot through the heel. It can really ruin your day. The way it manifests is that it is extremely painful to walk after any sort of rest, like sitting or sleeping. What happens is that when you have this condition, the inflamed tendon contracts from the rest since when at rest your foot usually straightens out. Think about it, when you sleep your feet tend to elongate. When this happens the tendon tightens. The first few steps after a rest period hurt like the dickens because now it has to stretch out and the rapid stretching and movement cause extreme pain. I endured this for about 2 years. I first went to a foot doctor who prescribed Celebrex. Yeah, the stuff that can cause a heart attack. It worked because those drugs inhibit the Cox 1 and 2 pathways, thus blocking the pain. Problem is once you stop taking it the pain comes back. Keep taking the medication for the long haul and your chances of a fatal heart attack increase.
As it turns out the things that helped me were changing my daily footwear choice and also wearing a night splint to bed. A night splint looks like an open ski boot. It keeps your foot/feet at a right angle, thus preventing the tendon from contracting. Over time this helps it to heal. For me the other great side effect is that I always tended to get a leg cramp in my left calf when sleeping, when my foot would elongate and cause the calf muscle to contract too hard. Man, THAT hurts for DAYS after a cramp. It wakes you out of a dead sleep into a screaming fit. (as well as anyone else within earshot)
The hard night splints did a job on the bedsheets and they are bulky and cumbersome. I found a nice soft Velcro one of Australian origin, made from kangaroo skin, which works like a charm. They are also MUCH cheaper than the hard plastic kind. You can find them on Ebay if you search for "Plantar Fasciitis" and/or "night splint", or "plantar splint" or something similar.
I also can't overstress the good that finding a different daily shoe did for me. I work in the IT field and get to wear Tshirts and jeans to work. Well, several years of sneakers didn't help me. I ended up, quite by accident, picking up a pair of Timberland hiking shoes on clearance at a local shoe outlet and I wear them everyday to work and I think it's more than a coincidence that my plantar tendon is so much better these days. I still get minor flareups when the weather is disagreeable or if I am literally on my feet all day. Being overweight doesn't help, but using night splints and finding the right footwear can pretty much cure this painful scourge of an ailment.
Hope this helps someone.