I had a cracked rib 1 month prior to diagnosis from getting out of a leaky QS air mattress - very painful. I have had osteoporosis for some years - I had a brief interlude with Bisphosphonates because of this which am willing to discuss further if you wish . I do not recommend that option.
As part of investigation prior to surgery a bone density test was done which confirmed a fracture and a very low t score.My medical onc later used this test to prescribe 6 monthly Prolia injections at the PBS price to counter the bone thinning of Aromatase Inhibitors.
I did not have chemo but understand from what I have read on the blog can cause bone problems. Others will probably comment on this aspect.
i did have 16 rounds of radiotherapy and have read that it does cause rib pain.Yes I have that problem - bearable but I notice it daily.
To complete the picture if you also have hormone therapy using Aromatase Inhibitors bone thinning is a major issue and that may include your ribs.
Good that you are getting it checked thoroughly. Wishing you the best and happy to chat further about this.