what core/oblique exercises can i do with slip-rib?

It's been a year since my slip rib started, my doctor had me on a high dose ibuprofen regime for 6 months but it didnt help.

Background to slip rib: One of my lower ribs is slipping under another rib, so there's a pop sometimes when I make twisting motions---there's no pain unless I repetitively do whatever is making it pop (which isn't always the same thing...but some examples where my rib usually pops is during bicycle-crunches, and even just bending sideways to reach into my bag on the floor).

I really want to get into whitewater kayaking which involves strengthening my core...particularly obliques, but I'm not sure how to do it and avoid popping sensations