I ran into a similar issue with tension picking up in my neck and upper sholder area. Especially after playing with accomplished players for extended periods. For example when I played late at an advanced session with no other drummers present. I found that it was because I was hunkered over the top of my drum. Listening as much to it as I was the other player and being melded with the music. I wasn't paying attention to posture or much of anything else just the drum and tune.
I found a solution. It came from my experience as a quitar player. I purchased a guitar footstool for my left foot to rest on; cost about $10.00. This raised the drum relative to my aa... ummm er I mean my buuu ... humm er ? aahhh my belt line. This in turned straightened my back as I played and got rid of the neck and sholder ache.
I also decided to loosen up my upper body a little when I played, I know tend to sway a little back and forth and move around; it keeps every thing a little looser and let me put more of me into the drum. Here's a link to the stand I picked up. It folds up easy and fits in the side pocket of my Bodhran case.
ProLine FreRest Delux Guitar Footstool
Hope this helps so you can ...
Enjoy Your Music,
Lee Marsh