Most likely to be "intercostal neuralgia".Sometimes a "post- herpetic neuralgia" can have similar presentation, without a rash(zoster sine herpete) . Do consult your doc.
Sorry, I meant, most likely
It might be a pinched nerve in your back. Do see your Dr. He/she will give you an exam and will like run some tests.
You need to make an appointment to see your doctor.