What can trigger frequent cold sore once every 2months? some years i get just one/year but since september i get 1 almost every 2-3 months. for the last year i used zovirax cream almost daily hoping to prevent them.could this made me more sensitive?

Increased oral herpes outbreaks can be triggered by common colds, illnesses with fever (that's why they're called cold sores and fever blisters). Sun contact can do it too; sunblock can help. Acyclovir (Zovirax) cream is not likely to be the reason. Preventive acyclovir or valacyclovir by mouth is effective prevention. See a doctor who understands herpes and can confirm with PCR test. Good luck.