Hi everyone,
let me start this thread with some information about me:
I am 28 years old and started with Pilates three years ago and autogenous training since seven years or so. I did Iyengar and Vinyasa Flow yoga for more than a year now, gradually doing more yoga than other sports, now approximately two or three times a week. Before I did Pilates I was a real office person with tension in the upper back, shoulders and lower neck. I had headaches very often and a bad posture. After my first Pilates class I found my shoulders have shifted to a different place, to the back and down, which resulted in some stretch sensations in my lower neck and some more headaches for some time. The tension disappeared after a few weeks and I enjoyed even more improvements in my posture.
Doing Yoga, mainly asanas, I sometimes had aches and pains related to my posture. First I had a De Quervain’s tendinitis in my left wrist, later some shoulder pain, probably in the rotator cuff, on the right side. Furthermore I had some problems with my knees. Taking care of my nutrition (low sodium, try to eat more veggies and fruit, a bit meat) and being careful with the asana practice, I managed to get rid of those aches and pains, one after the other, just in order to get the next one 
Recently I noticed that the tensions in the upper back disappeared completely and I think, my spine has become longer and less curvy there. My neck looks longer and my collar bones more horizontal. The tension seems to have wandered up my neck now :mad: When I move my neck I hear popping sounds, feel little tweaks and sometimes a bit of s resistance. Especially when I bend my head forward and turn it to a side, I feel a slight pain on that same side towards the front of my neck.
I noticed the tension can get worse in asanas that elongate the spine or where I am consciously taking care that my spine is nice and long and my chin tucked in slightly. It helps a bit to relax my shoulders completely.
Did anyone experience anything similar? I really hope that this is just some side effect of changes in my posture and goes away with some more gentle practice.