I have often felt the same result friend. like last week end, I played 20 sessions,not at once, but begun to feel my back,my neck,ect... all types of pains. I always had a tendency to get tensed in my neck and upper shoulder, could be how some of us are wired. even in practice. you are not alone in that ,and there is no shame in feeling like it is unimportant or silly to mention it, as a matter of a fact, it could be more important then find a holy grail system. because we are the instrument of the plays we make. I often thought of partner-play for that very same reason of the stress factor attached to performing a system. in a casino, one could be the applying agent of the system,like a quarter back, while the other be like a coach, watching and making the calls,(give and take).
it is one way to get you play higher stakes without stress.
another thing is for me, to apply yoga and stretching exercise. relaxation exercises is a must. a must do, in my case.
another point I like to make is the following;
i come back from a trip and have plays,numbers,ect...running in my head constantly. we need to create space in our mind to relaxe and "pause".
I play my guitare and it works magic,because it takes all my mind and heart into it.
what ever works for you to "get a brake from numbers" is what one must found. (apart from heavy drugs).