I'm having a similar thing... one particular run in October i got some shin pain which i normally run through (just ease off the pace a tad) but this time the pain radiated down into my foot. Ever since then I've had a burning pain right in the navicular area. Took a week out at the start of November - did nothing.. a week mid December did nothing, Saw the physio in Jan and took 3 weeks off. Physio says PTT right at the point of insertion, but after 3 weeks off says try a cheeky 3 miler at the weekend and see how it goes. On the one hand I like the way he wants to keep me running but i'm not sure its getting any better. Cheeky 3 miler was nice but its been a tad sore since then. I'm pretty much back to zero mileage wise and I've got the hackney half at the beginning of May! Good luck with yours mate, lets hope we all recover nice and quick.
Yes I can see your point, I do tend to have only one speed, which is gently as fast as I can go. Beyond looking at a basic training plan to push up mileage I've done research further than that. Thanks for the suggestions Cougie, time to read up.