 [ Symptoms ] i developed blisters that have grown and it is getting worse day by day [ Disease ] so sorry to hear you are going through this pain in the left arm and the back is always concerning in terms of whether it could be heart related if you are a woman please read this article about the possible symptoms of a heart attack which can include pain in the left shoulder and back along with weakness on that side if you are a man or a woman and are experiencing any of these symptoms please get checked out by a health care provider right away chest pain discomfort or heaviness pain or discomfort radiating to the back jaw or throat sweating nausea vomiting or dizziness extreme weakness anxiety or shortness of breath rapid or irregular heartbeats now all that said it is also possible you are suffering from a pinched nerve or muscle strain nonetheless if the pain persists gets worse or if you begin experiencing other symptoms please see a health care provider as soon as possible