I started suffering with PF after the Games 100, i think walking on pavements and tarmac for a good 40 odd miles, at a fast pace, was probably a large part of it.
I am glad to say after 3 months of trying numerous things i have found a system that works for me:
Stretch!!! As often as you can, but also especially before and after every event or practice session, it is difficult to stretch those tendons, best way i have found is to find some steps/stairs, and put your toes on the edge and drop your heels down, while either trying to remain 100% upright or leaning forward to stretch even further.
Shoes with orthotics, wear them ALL the time, put them on BEFORE you take your first step in the morning and take them off before you go to bed. I can recommend Superfeet Green Orthotics. I have also started to wear barefoot running shoes (Vibram 5 Fingers), which have the support and flexibility, not cheap, but i now wear them round the house as slippers.
I-C-E, Ice pack, Compression, Elevation, i do this after every event and every practice session.
Night Splints, there are a number of different products on the market, I have tried several, again at huge expense, they all work, but some work but because they are so bulky I couldn't get any sleep, the ones i found that i could actually sleep with were Futuro Night Splints, they weren't too expensive either
In the last month, i completed a 40 and 50 mile event with next to no pain :)
I still wake up some mornings with a little pain in that first step, but nowhere near what i had 3 months ago, it apparently takes anything from 6-12 months to totally get rid of it, it is truly a horrible affliction, you have my sympathies.