Erectile dysfunction

I am 45 years old, in my childhood i was getting very hard erection,1st time i sex with professional woman, and i was so scared to get disease.as a result i went to the doctor and doctor ask me if i have sex with dirty woman. and i said yes, he put injection n also gave me tablet, i was so shy n horrified, one year passed but it was same, i keep eating tablets, i never get erection as well,one day i told my friend n he ask me to show my penis and i showed him, he laughed n told me, you have nothing, see i am also having small boils here, n i realized, that dr. is cheating me.and also misguide me. but it was too late.i was badly smoking n was also chewing tobacco.once i had blood vomit, again i went to doctor n doctor told me i have an tuberculosis, i ate medicine for 9 months. when i show my report to other doctor he said you have no tuberculosis. so i cheated two time by two doctors.gradually i got sound health, than i met one girl n we became friends, and i try to sex, but my penis not erect properly, i took testosterone injection.it little works, than i did sex with my girlfriend but it was for 2 minute, than i also ate lycopodium, but not much result.if i am lying position i get some erection but if i stand up, i loss erection, why?only sildenafil citrate is giving good result. but i hear that it is not good for health. i am tired now.please help me. i will be thankful to you.