Until last week I suffered neck & shoulder pain after every sewing session as well. Last Thursday I took delivery of a sewing table (SewEzi - no affiliation) and now no pain ! And I have been sewing for hours and hours as I am learning FMQ. The table, which is exactly the same height as the table I was sewing at before, allows for my machine to be recessed so it is flush with the table top. Lowering the machine those 4 or 5 inches made all the difference.
I read somewhere that for good ergonomics, if you bend your arms so that your forearm is parallel to the floor your sewing surface should be "just" below your arm. So you end up with a very slight downward slope from your elbow to your hands at the machine. It may not make a difference to some people but it made the world of difference to me.