What Causes Sharp Pain In Left Chest Area And Painful Breathing?

I am an 83 year old female and have Gerd and an hiatal hernia. For the past 48 hours + I have had a sharp pain in my left chest area just under the lowest rib. Positional changes are painful as well as deep breathing or coupling. The pain goes all the war through to my bak shoulder blade and below. I have an appointment with an Internal Medicine Doctor tomorrow, but don t know what tests to ask for. Can you help me? I have no nausea, little apetitete, no fever. I have no history of heart trouble, but am on Coumadin because of a blood clot/stroke causing only a blind spot which happened 17 years ago. Thank you.