This does not sound like a cracked rib. A cracked rib would be very pain sensitive right at the time of injury, it wouldn't be OK then get worse over the next few days. This sounds like a subluxed (partially dislocated on a small scale) rib. This diagnosis would account for the pain you're describing as well as the small lump under the breast. I would go have it x-rayed to confirm that it's not fractured (just in case) then if not fractured go see a manual physical therapist. You have some great one's in Norway. They should be able to relocate the rib, if that is what's wrong and get you back on the right track to healing.
Hope that helps.
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