Never had anything like this before. Around 2pm today (almost 12 hours ago) I started having discomfort on my left side (in my lower ribs). Any type of movement causes discomfort as well as inhaling deep breathes. There was no injury to the area at all. I work nights, so half way through my shift, when standing, I noticed that there is a had lump that seems to curve underneath the rib. This lump is very tender, and when presses causes sudden stabbing pain for a few seconds. It isn t visible, you have to feel for it (it appears to be on the end of the rib and curves underneath) Any ideas on what this could be? I am at work until 4am (should I go to the ER afterwards or wait until tomorrow and go to a walk in clinic?