correcting my bad neck posture (side slant)

I posted yesterday but it does not seem to have appeared.

My neck slants to the right. This happened or became noticable in the last 3 weeks. I may have injured my upper left trapezius somehow, the doctor today said it was possible. He also said that most people have some imbalance in their necks and da da da basically that I should get used to it and exercise more (I exercise 6 days per week - powerlifting then cardio 3 days then yoga 3 days per week). I think this happened one night while I slept awkwardly. It may also have happened while I was deadlifting or doing high-bar squats.

I want to know how to fix this. I just don't feel right with a crooked neck.

If I build up my traps and do neck exercises in the opposite plane will this work? What if I do a lot of long stretching i.e. with my left ear towards my left shoulder? What if I sleep on my left side for one night with no pillow, so that my neck is bent in the other direction?

I would be grateful if someone could give me some help about this.

Also, why was my first post not let through?
Additional Comment I forgot:
strange, the first time I posted it said something about needing to be moderated...and this time it appeared first time.