Having some pain 19+2

I had some sharp pain to the right of my belly button that wasn't constant, it was on and off. I didn't think anything of it and let it go because I thought it might go away. Tonight I'm feeling kinda nauseated now and it is tender in the same spot. I'm worried that I may have hurt something because a few days ago, I stupidly hefted a really heavy box down the stairs and to the garage. I'm not bleeding and I don't think I've got a fever. I have a big ultrasound on Monday (anatomy scan). Do I wait it out? and is there anything I should be looking out for?