Hi, thanks for writing to HCM.Costochondritis
and your shoulder problem, back pain are UNRELATED.
Costochondritis is a self limiting condition that responds well to appropriate antibiotic, analgesic
antiinflammatory medication, ice pack compressions etc.
The cause of your shoulder numbness
could be in the Cervical spine
or the Shoulder perse.
You need an MRI scan to make a diagnosis.
Hope this information is helpful. Good day