Pain in top left part of back

I have had costochondritis for the past six months and the pain in my chest just started back up again this past weekend. Over the course of this week, my top left back has been hurting as well and I thought it might have been from the costochondritis or heartburn I have had over the past few days. This past weekend, I went to a friends wedding where I drank a little alcohol which gives me bad heartburn. Since going to that wedding, I have also noticed that when I swallow large pieces of food it hurts the top left of my back. I don't know where this back pain has come from because it just started happening this weekend along with my costochondritis. I know I have been VERY stressed lately and I have had bad anxiety after starting my new job this week. My sleeping habits have been very bad lately also because my new cat has been waking me up almost every night. The pain in my back is very annoying but seems to go away and then come back. It usually occurs when I am sitting down for long periods of time but doesn't affect me when I am standing up. I had this same back pain yesterday all day but when I went to work and were standing up for 5 hours straight it didn't bother me once. My back doesn't hurt me when I drink water, juice, etc but occasionally when I eating something large. The pain in my back seems to be between my left shoulder blade and the top of my spine.

Not sure what's going on with me but I would like to know.