@abbyk My 1st thought was that your family physician retest your bloods to be sure there isn't any changes and ensure no cancer, and tumor pressing etc, just to ensure nothing else medically going on.
If not and everything tends to be on one side still, my 2nd thought was it sounds like you are off balance like Jennifer mentioned so neurologically, it's affecting one side of your body. It's amazing what a good chiropractic alignment can do, but I'd add massage therapy to that for sure. I've also tried acupuncture. Mayo's Integrated Medicine does both, but will only see you 12 times for each. Insurance doesn't always pay. For massage, I found joining Massage Envy was cheaper. If misalignment is pressing on the nerves on one side, that will cause things to affect one side of the body.
When my neck was misaligned from a minor car accident, 9 months of PT didn't do much–strengthening only made things worse. It was just that I wasn't ready for PT yet. I'd also suffered with constant sinus infections. I was nervous having someone touch my neck, but someone who will be gentle would be wise. Once I got aligned, the nerves being compressed settled down and stopped headaches, ear and head pressure, jaw pain, upper back spasms, etc. besides the sore neck and back muscles.
The problem left though was given the time I spent crooked, the muscles on one side has shortened and the muscles on the other side of my spine had been stretched for so long that it took several months to slowly get them back in place. That's why I feel chiro only isn't enough.
If you are able, also try gentle yoga stretches, short warm baths in Epson salts to relax the muscles (brief hot tub/steam room), and lots and lots of water.
I was also advised to watch how I slept, so I wasn't tilting my neck one direction for hours while I slept nor having one arm up, either adding to neck and shoulder strain. I had to switch to starting off as a back sleeper, with a softer and less filled pillow to support my neck and not tilt my neck at any angle, and a pillow under my knees; then when shifting to my side, to be sure again my neck was supported but not tilted and the pillow moved between my knees to ensure my hips stayed even and didn't pull on my back. All that helps keep the spine aligned.