I don't know if it's the same thing, but I've had inflamation of the ribs below the breast on the right side. The doc has said musculo/skeletal, then ignored me. I've wondered if it wasn't costo or not. However, after lots of research on my own, just a few weeks ago I decided it's probably lymph related. There are two lymph reservoirs, and one is by the liver. This rib inflamation when it's at its worst is when the lymph on that side of my body is bothering me the most (like the lymph in the arm pit or alongside the right breast). Liver Flush temporarily helps, but doesn't permanently fix. So I've started doing things to help the lymph system to begin draining better, and it seems the swelling has decreased some.
During my research, I came across lots of women who had problems with pain and swelling in the ribs below the breasts, but the doctors always said it was nothing after ruling out liver/gall bladder issues. But we were all in lots of pain over it. One of the things I saw was in common for all these women is that this area had a lot of pressure put on it by bras (or from the other direction, a baby during pregnancy). With the liver lymph reservoir right there, and it getting extra pressures that could cause blockage, I was suspicious that it was lymph. THEN when I read that lymph problems often show up after a surgery, that was my AH HA! My swelling started 2 weeks after I had a breast reduction surgery (on a side note, that surgery has relieved me of much pain and nerve issues, so I'm very glad I did it). It wasn't the surgery itself ... the doc didn't do anything there, and he couldn't recall from the way I was moved around anything that would have done such damage. But, having surgery itself (or even being sickly or toxic or overweight) puts a burden on the lymph system. I think it was just too much for me, and thus the problems.
I wonder if you had the backslide with the costo ... if it's actually a lymph problem ... because of maybe going lax with the "cleansing system" you'd set up for yourself, so you got toxic enough again that it put too much of a burden on your lymph system?