Threw out my back yesterday, advice?

Was trying to be a good hostess at my baby shower and helped set up and entertained our guests, so I didn’t sit down until the opening of the gifts. At some point my back just gave out from bending down to reach into the bags. This morning I thought I was feeling better so I went to go through the gifts and separate everything, well I bent down and my back gave out again and even worse. Now I cant move without shooting stabbing pains in my lower back, my check up is tomorrow so I was going to wait and go and tell him then, but is there anything I can do in the meantime to help the pain?