Cupid, it certainly sounds like sciatica from a possible lumbar disc problem. Not a straightforward condition to treat and with variable results.
He needs an MRI scan to formulate a definitive diagnosis and ultimate treatment.
I agree with the Dr that simple analgesics such as co-codamol is the correct management at the moment and then the situation should be monitored.If there is no improvement, then he made need phsiotherapy or perhaps operation depending on the results of the MRI scan.
Keep us informed.