Could this be a gall bladder attack?

I have an appointment with my doctor tomorrow (she couldn’t fit me in today), but in the meantime:

I woke up yesterday with pain just under my ribs in the center of my chest, near my xyphoid process. It’s severe enough that I can’t seem to catch my breath. No vomiting or diarrhea, but some sharp pains in my back, too. It gets a bit better with ibuprofen, but it’s been 2 days now and it hasn’t gone away!