I slept on my stomach today. This morning my left breast is very pain…

I slept on my stomach today. This morning my left breast is very painful, there's no strong swelling but it's incredibly painful even when touched. I want to express milk but it comes out very little, although I always had a lot of milk on this breast. This morning I put the baby in this breast but there's no relief at all. I'm going to see a mammologist on Tuesday. What should I do until then?