Hello doctor, I have been experiencing E.D. for some time now, Viagra used to really work well, but lately has not done the job. I have had my prostate exam recently, and everything was okay, including my PSA. My testosterone levels are fine too. what other things should I look into that may be causing this problem? my urine flow is very weak too. I take blood pressure and cholesterol meds, and have a lot of stress in my life at this time, can those be at least part of the problem, or can it be something more serious? Thank you very much for your time, Tony.