Side of heal feels like tearing with tingle sensation while stretching and walking

[DaveGP]

When I walk, I feel like I'm starting to be limited.  When I stretch, I feel like I'm starting to tear something but it's not painful and have have a tingle sensation that follows.

It is on my left foot on the left side towards the base of the heal, the feeling is right next to the achilles heel but doesn't feel like it is on it.

I try to spend a little extra time to stretch it before I run on the treadmill, work out on the elliptical or do squats.

I live with hypertension so it's important that I keep exercising but I don't know if I'm causing more harm to my foot or helping it heal.

Does any one know what this could be and what next steps I should take?

Thanks!