<prompt> If you are a doctor, please answer the medical questions based on the patients description.I had a gym work out yesterday and as soon as i went to put my coat on, i felt what i can decribe as a lump on my left shoulder blade, like its under the shoulder blade. i can use my left arm without problems but the whole shoulder blade area is very sore.  <response>: Muscle or tendon tear! Yes, that is the brief answer to your question! Thanks for giving me another opportunity on sudden painful lumps in this forum... But dont worry; rest of the specific area along with cold compressice could relieve this in 23 days; dont rubmassage it to invite infections! It is related to minor trauma, sprains, strains or even tearedemasilent bleeding while doing strenuous movements and no way this could be serious! Take care; regards, 