From what you have described, it could either be a Left Frontal Sinusitis or some sort of neurological disorder. It could be an eye problem as well. If you also have symptoms like runny/blocked/partially blocked nose, thick nasal discharge, mild/recurrent fever, fatigue, and nausea it is probably sinusitis. Well, it's really difficult to tell what the actual problem is without diagnosis. What you can do is search the internet and try finding the symptoms for sinusitis/neurological disorders/vision problems and trying matching your symptoms with the ones given there. One good website is perhaps
www.mayoclinic.com. Finally, if not smoking relieves the pain then you should stop smoking (even though it's much easier said than done but you can always do that if you are strongly determined). Hope that helps somewhat. God bless you!