I found out that I have ED 2 years ago and one of my doctor back in india gave 20 mg viagra. It did not work efficiently to my body then he suggested 100mg dose. it really worked wonders for 2 years but from last week I have high ED despite taking 100mg viagra. Perhaps my body might have built resistance to that or don't know what the case. should I increase dosage to 150mg? I'm 29 year old healthy male without any health issues in past but once I found out my testosterone was bit less than estrogen. I need strong and hard penis for happy sex life but ED has hampered my love relationship to great extent. Please suggest me something