Dear friend, welcome and thanks for entrusting your query here at HCM !
It is definitely related to your injury.
Was a CT scan of the thorax or spine done at that time?
Did the pneumothorax
need drainage/ ICD then?
It may be underlying soft tissue
trauma or sometimes a missed spinal injury
that may be causing trouble now.
If it is electric like , intermittent pain , it could be intercostal neuralgia- a pain due to nerve injury
to the rib related nerves.
You should get thoroughly evaluated by a physical, Xray chest PA and lateral and may be a CT scan thorax and spine if clinically appropriate.
Rib fractures usually unite in a month and the pain should go away.
So this could be something else.
Please post any old reports to give us more details to comment on.
Rare possibilities are a delayed hematoma
, paraspinal injuries etc.
I hope you are fully satisfied with the guidance I gave.
I would be glad to answer any further queries.
Thank you and Good luck !