Sorry you are in such pain, Jim. A couple of years ago I started having plantar fasciitis and tried a lot of things to cure it. It got better but never did heal completely. There were times the pain was unbearable. Like having a nail hammered into the arch of my foot then next day letting your foot go through frostbite radiate from the arch out. Rinse and Repeat. Terrible.
The problem with foot issues especially if it is tendon inflammation-- is that they are hard to cure. Very little blood goes to your tendons and so pain meds cannot get there to de-inflame it. Same with topical creams. Perhaps consider cortisone injections. There are pros and cons to that such as steroid induced weakness/damage to tendons. As a runner I opted not to do that since I risked tearing it altogether later. And as we get older or have diabetes blood supply problems happens in the feet first so don't add further injury when possible.
Maxtog, sorry I misunderstood. I wasn't speaking of diclofenac creams. I thought you were taking the rx pills/cream. Pills can cause holes in the stomach. The cream will thin out your skin though. My doc had me take both with restrictions. The cream (useless) 2 weeks on and 1 week off. If the cream worked for you it may not be tendinitis, just soft tissue injury. Good news.
I would still recommend you seeking 2nd opinion from a (sport med) orthopedic doc. They have in-depth knowledge of the musculoskeletal system. Just don't have them butcher you like in that vid