Why does my volume drop down?

[Windows Central Question]

When I go for a run or a walk my volume either turns down half way or completely to zero. A couple weeks ago I was traveling and as soon we started taxiing on the runway, my volume plummeted to zero and I couldn't listen to anything the whole plane ride.

Nothing is pressing on the buttons and I've tried to check settings to see if there was a GPS issue but I cant see anything.

I had this issue towards the end of my last windows phone so now I'm wondering if it is an account issue?

 

[ML10]

Maybe the button is stuck?

Seems unlikely though but when you go running with an armband then maybe it popped the button in such a way that it gets stuck.

The airplane situation is weird though.