Hi ostnc,
Have you ever had an x-ray of your feet to determine if there is any bony abnormality?
It does sound like plantar fasciitis (note that this can be felt from the base of the calcaneal right up to the ball of the foot, many people think it is only experienced under the mid-foot) - when you walk bare foot you have no support whatsoever for either of your arches in the foot, therefore this can cause stretching of the fascia.
What it could also be (likely if it is bilateral) is a small bony spur that could be digging into the fascia, this would also cause similar symptoms and would need to be ruled out by x-ray.
Have you seen any specialists, podiatrists or physiotherapists about this problem? I would strongly suggest this if you can, many GP's wouldn't really know where to start with this type of problem which is probably why you've been fobbed off with no diagnoses and very little in the way of advice and information.
Unfortunately I can't really give you any hard and fast suggestions for rehab without doing an assessment to find out what exactly is causing the problem, but I am sure if you can see one of the above healtcare professionals they will be able to help you out. good luck, and please let us know how you get on!
Ruth Cheesley BSc(Hons) MSc MCSP
Chartered Physiotherapist