I Have Had Recent Discomfort On My Lowest Left Rib

I have had recent discomfort on my lowest left rib for the fast week and have noticed that the left rib is more inflated than my right rib pretty significantly, but never knew if they were like that before or not. I have also found that when I lean to my left side in certain ways, it becomes more discomforting and has little pain. Today I noticed that the area is a little sore without having to touch it and is getting more discomforting. The area is not colored differently or looks differently besides the fact it's more inflated. I have recently moved to college, and have been eating a little less healthy, but not much differently than usually. I have very good blood pressure and I weight 145 and I'm the age of 18, thanks for helping me.