Hi.
I occasionally get very intense pain in the back of my head when I exercise. The strangest thing is that I always get it when I'm using the same machine: The Pull Down Machine, which works the back muscles.
I got this pain again today, and I recall noticing that my chest felt a bit, I don't know, fragile.

My best guess to the cause of this pain is insufficient Oxygen reaching the brain when I overwork myself.
If this is true, why then has it only happened when I'm working on ONE machine? Coincidence, perhaps?

And if some personal information about me is needed, I am 19 and in decent shape.

Any information would be well received.
Thank you.

Also, I put this in the Medicine section since I did not get a response for it in the Pain Management section. Sorry if this questions seems a bit out of place.