re: Sudden decrease in strength (left side)

Keep in mind nerve regeneration occurs at a rate bt 1-2's mm per day when for cutting injuries and such.

Have you had a previous spinal cord injury? How does your neck feel? Hopefully you don't need a laminectomy.

Btw compression bt c5-c7 spine can affect the movements you are describing. Elbow extension (triceps as in dips) is c7. So if you had a spinal cord injury (sci) at c7, you can expect to have an absence of or difficulty extending your elbow