About 10 years ago I had dreadful pain in the ball of my foot when walking. GP sent me for x-ray, then to a podiatrist. I saw one podiatrist after another. One pointed out one leg leg was an inch longer than the other, so built up the insole on the shorter side shoe as this must have been causing the problem. I couldn't stand it for longer than a couple of days, due to worse pain, and had to rip off the insert. Another podiatrist tried acupuncture and was delighted to find I had muscle-grip when she pulled out the needles, which is rare but causes pain. Unfortunately acupuncture didn't help either. Eventually I was referred to a consultant podiatrist who referred me for an MRI scan. This found a few things that could be causing the pain, thankfully none of them permanent or serious.
if you haven't already had an MRI, you should ask to be referred to a consultant.