I have just had similar discussion with another person on here. I am not a professional but it sounds like Slipping Rib Syndrome. It is rare. MRIs are not helpful. SRS specialists can see it on regular CT abd/chest without contrast, but the untrained eye can easily see the fractured cartilage once the CT is converted to 3D. It is when one or all of the false ribs 8-10 have fractured cartilage and the loose ribs slip on overlying nerves. Very painful with a wide range of symptoms. It can be left, right or bilateral. Extremely painful and debilitating. It is rare and most doctors are unfamiliar. I had 5 years of normal tests before I self diagnosed, found a Facebook administrator who converted my CT to 3D and saw a SRS surgeon. Please check it out. There are 2 Facebook groups SRS Info Outreach and the other Slipping Rib Syndrome. They can help you convert your CT to 3D and advise seeing a doctor from the list of SRS surgeons which are few and scattered across the country.
Good luck. Hope this helps.