I'm sorry you're going through all this, I can empathize on this.

Life does make things seem limited due to work and household share.
How is your relationship with the husband beside the chore issue? It's something worth talking about.
As for the stiff neck, if doctors can't figure a cause for it, it's probably from depression, as it causes physical pains in various areas, the neck being one of them. The fact that running makes you feel in control is great, it means it's a combat against the depression. Keep at it!
And if you feel like the small fish in a pond, then how about taking the time to practice at home? It will allow you time to learn, grow and enjoy on your own without the distraction of other's abilities, and relieve your exhaustion.