Back pain that changes location

Female age 27. Pain started about 2 week ago. For starters, I am seeing my doctor next week, but I’m looking to see if anyone has had similar pain.

I’ve been having pain in my back, but not in one specific location. It first started in my middle back on both sides. It was an aching sensation. I tried pressing on my back and couldn’t find a pain location. The pain comes and goes. I notice it more with sitting (I sit a lot at a desk) but sometimes the pain is felt higher up between my shoulder blades, almost directly in my spine, or on either side of my spine and is aching. Again, can’t find the pain location, and I don’t notice any changes to the pain with movement. I have been basically living with a heat pad on my back. I did go to a clinic and the doctor said it was muscle strain (he barely asked me any questions so I’m hesitant to believe him)

Any thoughts on what this could be?