pain in jaws could be for various reasons it could be because of an organic cause like tooth decay or gum inflammation or periodontal destruction. it can also be due to habits like bruxism or night grinding or svere attrition continuous use of tobacco also  results in submucous oral fibrosis. since the question is in general,the exact cause has to be traced another factor is trauma to the tooth or jaws or tmj! a clinical diagnosis is a must,till than try to minimize ur smoking habit and maintain a proper oral hygiene regime!