For A Few Years I Have Noticed A Pop Like

For a few years I have noticed a pop like sensation on the lower left rib cage. It was occasional and sporadic so I never got it checked. Now about 4-5 months after having my first baby, I notice the popping sensation a lot more often, and there is minor sore pain. Occasionally it is sharp pain too that radiates various areas of my side. It isn't bad enough to disrupt activities but I'm a bit worried as to what is causing these sensations/pain feelings? As an FYI, I was 119lb, went up to 150, maybe close to 160 during pregnancy, but I don't remember, and then dropped again to 119lbs postpartum.