Suggest Medication For Headache Despite Taking Gabapentin

I have severe headaches from my sinuses. I have had a scan and they found nothing except my doctor told me it was inflammation. I was prescribed pills Gabapentin. i am currently taking 2100mg per day without success. These headaches have been going on for the past five months. In the beginning I was taking up to one hundred Tylenol 500 mg per month before getting my medication. It s not as bad now until I cough, sneeze, bend down, then I get severe shocks to the head, and often remain with a slight headache till I go to bed. It seems that the pain reduces when I lay down. Then I can clear the fleme in my throat and clear by coughing. I have been taking these pills for the past month. Is there a rapid way of clearing my sinuses other than steam because I also do that daily. Maybe a deep secret that I don t know of. Thanks very much I am a senior of 77 years old and definitely not imagining the pain.