Thanks for your question on HCM.
I can understand your situation and problem.
The lump you are talking about is mostly callus
Whenever bone is injured, either fracture
or hairline crack, there is healing by callus formation.
After bone injury
, inflammatory mediators reach to the site, there is calcium deposition to fill the injured area. This calcium deposition occur in circular manner and give rise to impression of swelling or lump.
This will slowly decrease and dissolve over time.
In my opinion, you should get done chest x ray
for her to rule out internal lung or rib damage.
If this is normal then no need to worry for this swelling.