My undiagnosed foot/gait issue on left side

[Redpanda7]

I've been a runner for over 7 years now and I've started to have this weird symptom on my left foot without any injury since Nov 2013.
I visited many Dr.s and specialists to figure out what's wrong with my left foot, but unfortunately, none of them were able to diagnose to this day.
The symptom in the last 2 years has gotten worse gradually and now my gait is affected a lot to the point that I’m struggling to walk even for 5 minutes without dragging my left foot or I start to limp severely when there is any stairs up/down or any slight inclines on the ground.
Hoping if anyone has some insights to figure out what's causing, what I should do or whom I should see from the history of symptoms/testing below.

History of testing
MRI brain --> came up normal
MRI spine --> came up normal
Blood test --> came up normal
Physical muscle/nerve test --> came up normal
Electricity nerve conduct test --> came up normal

History of Dr.s
2 x Family Dr. --> No conclusion
1 x Podiatrist --> No conclusion
4 x Sports Dr --> No conclusion
2 x Physiotherapist --> No conclusion

It's been 5 years since I noticed a slight symptom and now I can't live normally without normal gait anymore.

Hoping to have answers to this or cure.