Hello There is severe pain in the shin of TIBIA but you didn t mention the duration of pain . You are taking neurontin 600 mg i.e Gabapentin .Usually this drug is prescribe in as adjunctive treatment of partial seizures not satisfactorily controlled with other antileptics. While gabapentine is also used as a pain killer as may be in your case. The pain in shin of tibia may be due to these reasons , these includes. 1 Osteomyelitis , as in early & acute stage this disease causes sever pain in bone ( as in your case may be ) . Diagnosis can be confirmed by physical examination by an orthopedic surgeon . C T Scan is also important in this case.Blood examination for C B C & E S R ( if very high suggestive). 2 Deficiency of calcium may be the another reason of such pain . Get in blood examination for calcium as well Vitamin D ( cholecalciferol ) deficiency for any osteoporosis . 3 Sequestrum a piece of dead bone tissue formed within a diseased or injured bone ( note down any blunt injury in recent past. In my opinion consult one more orthopedic surgeon and get his opinion ( 2nd). Good luck.