Starting two days ago excruciating pain developed on my left side starting at the shoulder now the entire left side of my body what could it be?

Left side pain: May be thoracic outlet (usually just upper arm) , TMJ, Rarely vascular-clot ,stenosis ( pulses Ok on the left??) rarely stroke if have difficulty moving, -rare in young unless autoimmune. Could be beginning shingles and rash will come out in a few days . may also be MS, , constipation, colon process,autoimmune. GERD/ reflux -H py;lori (try ranitidine) Need MRI ESR ,CRP, ANA dsDNA f/u /w/ doc