Cor - could be a bunch of other (& more probable) things.
Peroneal muscle/tendon, Common Peroneal Nerve, joint stiffness, poor loading, poor control, dodgy mechanics (deffo), sural nerve, odd things going on with your back.
It's easy to feel better (go stretch) more tricky to get better.....
Agree with Tricia - it's not OA. Clicking ain't no problem and doesn't relate to anything as long as it's not a painful click.
Have a try of this....https://www.sixphysio.com/video/running/self-tape-your-knee-mcconnell-patella-taping
Sure it's sural nerve and nothing else?
Go and find someone decent who can examine you properly, relate your pain to pathology (or not) and get on and not just treat the symptoms but deal with the underlying cause.
I'd stop stretching as it's pretty obvs it's not doing very much, and on that basis is more likely to be prolonging your symptoms...
You are not out of shape after 4 days hang time.
You're doing far too much and probably have done if for far too long too. Less is more - variety is the spice of life. Let you body recover, get out side and do something different.
Oh, and try this https://www.sixphysio.com/video/back-pain/theworldsgreateststretch
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