Suggest Treatment For Back Pain And Pain Under Shoulder Blade

On Sunday I stated with back pain after carrying my toddler around. I asumed pulled muscle & tried to go easy. On Wednesday the pain was still there, but fairly dull untill. I had to put pressure on a table leg to put it in place (fold up table) I litrally felt something in my back pop where the dull pain had been, it was straight away followed by a winded, breathlessness for 5 minutes & since I have been in absolute agony. The pain is on my left side, just under my shoulder blade. I ve had many pulled muscles from working in fitness, but this pain is more severe than anything I have ever experienced. Not even convinced it s as simple as a pulled muscle. Please help. I have a doctors appointment booked. Thanks.