Post cardiac surgery pain

Greatings to all!
These questions may have been answered, so I apologize if the answers are staring at me.
I had a mitral valve repair about 2 months ago. Thank God, everything went fine. Stamina, exercise tolerance improving. Still run out of energy in afternoons, but I suspect that will improve. Incisional pain still present but I know it will improve. My biggest issue is the mid to low thoracic, posterior, back pain. By early afternoon it's pretty uncomfortable. I can walk 6 miles, no problem. Working a few hours on my feet is bad. For instance, now it's 4 pm, and I have to sit with lots of lumbar support and take 10-20 mg norco to get it tolerable....earlier in day I am fine. Though the pain is way better than a month ago, it's pretty frustrating.

I under stand this pain is probably due to the spreading of my chest, potentially broken posterior rib articulations, etc. my question is how long others have experienced these such pains? No fever or other illness. I have normal coronaries. The mitral repair was perfect, hardly any insufficiency left. Surgery was due to progressive MVP. I'm 57 years old, male.

Granted I'm a whimp and whining too much but learning what others might have experienced is appreciated.