I was experiencing upper back pain these days especially in the shoulder blades area so i started to do stretching and jump ropes. i noticed that when i'm lifting my right elbow, my left cheek lifts involuntarily. everytime.is this condition serious?

Yours is a very odd symptom complex, but occurrence of interscapular pain together with linkage of a voluntary movement below the neck with a contralateral involuntary movement above the neck suggests the POSSIBILITY (only) of a problem either in the neck, above it, or both. You should not ignore this. You should see a neurologist for a workup so that a significant problem can be ruled in or out.