Recent endoscopy normal. on rx antacid 7 years chronic post nasal drip, sinusitis. could i still have lpr? who would diagnosis it?

Yes you can: LPR is often missed even with pH monitoring which usually covers only the lower part of the esophagus. If you do not have chronic sinusitis (proven by CT scan), consult a GI doctor (sometimes an ENT doctor can diagnose the condition as well).

LPR: You could have rhinitis medicamentosa or a post nasal drip caused by the verapamil you are taking. Talk to your foctor or see an allergist