You likely need magnesium. It's almost impossible to get enough in our diets so we need to supplement. Mag deficiency contributes to plantar fasciitis. Without enough magnesium, the calcium in our bodies can be absorbed and gets pushed into the soft tissues and this can contribute to PF.

It may not take all the pain away but in time, it should help. You want to use a quality form like magnesium malate. The malic acid in magnesium malate is very beneficial for athletes too.
Have you tried doing Epsom salt foot soaks? Or spray your feet with magnesium oil? This is a way to get magnesium into your body and also localized areas. Plantar Fasciitis Treatment | Treatment for Plantar Fasciitis Symptoms, Diagnosis - Denver

Have you ever tried a compounded cream from a compounding pharmacy? Here are some recipes

keto- ketoprofin, an nsaid
ketam- ketamine
Keto 20%/ Ib 2%/ Ketam 2%/ Clonidine 0.2%/ Amitriptyline 2%/
Guaifenesin 2%/ Topical Cream

Keto 10%/ Guaifenesin 10%/ Capsaicin 0.025%/ Lidocaine2%/ Amitriptyli 2%

Keto 10%/ Cyclobenzaprine 2% Topical Cream

Baclofen 5%/ Ketoprofen 10%/ Lidocaine 5%/ Gabapentin 5% Cream

Amitriptyline 2%/ Keto 2%/ Carbamazepine 2% Topical Cream
http://www.compoundingdocs.com/uploa...asciitisRx.doc