Question: I am a male, 28, 6'4'', 165lb, mild hypertension, ADHD, but otherwise in good health.
Medications (same for many years): Lisinipril 10mg, Vyvanse 40mg, Zenzedi 15mg
Approximately one month ago while waking, I went to preform a full body stretch (arms above head, legs straight, toes pointed), I do this occasionally without issue. This time I felt a muscle strain begin to develop in my left calf.
I've had such strains in that area before and typically just bring my foot upward, bending at the ankle, and the pain usually levels out, then fades, with some remaining soreness.
This time however, the pain grew into an antagonizing, screaming, writhing in bed kind of pain. After 15 sec or so I was able to relax my calf and the pain stopped growing. My calf was extremely sore for the entire day and half of the next. I didn't think much of it after the soreness went away.
About a week later, again while waking up, the same thing happened. This time the moment I felt the strain begin, I immediately relaxed my calf, which did stop the pain, but I still had mild soreness for a few hours after.
Thinking it must be a vitamin issue, I began to take a daily multi-vitamin.
A few days later I was using a screw driver in my right hand when I felt a strain forming in the abductor pollicis brevis region. The pain again, was intense, causing me to drop what I was doing. I also couldn't seem to move my thumb out of the position I had it in while holding the screw driver. After several seconds the pain turned to soreness and I was able to move my thumb.
The next day, while yawning I felt a strain forming in my jaw muscle. I immediately ceased the yawn and thankfully the pain subsided. It was not a particularly wide yawn.
These strain occurrences started happening more and more frequently, in many parts of my body.

It doesn't seem to be triggered by just using the muscle.
I can pick up heavy objects, tense my muscles, tighten my grip, all without pain, but if I do even a small amount of stretching with any muscle, I can start to feel a strain forming, which stops when I stop the stretch.

Things that trigger the strains, and the areas of pain:
Crossing my legs: Calf, Thigh, Shin
Yawning: Jaw
Giving a thumbs up: Hand/Base of thumb
Lifting my thumb back: Hand/Base of thumb, wrist, fore arm, bicep
Turning my head to the side: Neck
Lifting my toes: Exterior Shin
Pointing my toes: Arch/Ball of foot, base of big toe, Calf
Dangling my foot from a high seat: Ankle

I do not get a lot of sun, and in the past, have been told that my D levels are on the low-normal end.
I did see low D listed as a possible cause when researching symptoms, so I started taking D3 2000 IU last week.
A week after taking D everyday, my calfs do require more effort to start a strain, but I'm unsure if it's related.
Other locations, such as the thumb, foot and ankle, still begin to strain with minimal stretching.

Is it low D? or some other deficiency?
What could it be, and how should I proceed?