Right side pain under ribcage, is it my gallbladder or something else?

Sounds like your gallbladder. I had surgery for this many years ago. If it is your gallbladder the pain will continue to worsen and you will feel nausea and vomiting will occur as it gets worse. Your surgeon will decide by the test he runs and if it is gallbladder, surgery is the only cure. However, today they can remove the gallbladder with laproscopic surgery which is minimal and you can go home that night, if you do well. Good luck to you.