There are many things that either cause or aggravate ED. A few of the most common ones are:
a medication you may take for something else; some blood pressure meds, may others
smoking; alcohol abuse
excessive caffeine intake from coffee or soft drinks
stress and life changes - either at home or at work. Job problems, divorce, etc.
diabetes; vascular insufficiencies caused by aging or other diseases
In my experience, most general practitioners do not know as much about ED as most urologists do. That having been said, some urologists don’t know a whole lot about ED even though we assume they are trained well in the subject.
There are (in nearly every large metropolitan area) urologists who have a special interest and training in ED. You can easily find one in the Yellow Pages (physicians; urologists) since most of those who specialize mention this now in their advertisements on those pages. Or ask your GP to refer you to one that he/she knows. Your health insurance will pay most of the cost of the visit, and if you ask questions you will learn things.
Some of the ED drug manufacturers - the major ones are Lilly, Pfizer, and Bayer - offer special financial incentives to those who cannot afford the retail price of their drugs. You may qualify for one of those programs. Further, it may be that Viagra is not the best drug for your case and that Levitra or Cialis might give you a better run for your money.
Although certain methods of PE can help a lot in turning around a compromised penile vascular system, don’t expect a miracle cure from it. You may well improve your erectile function through PE, but if your problem is organic and more than moderate, odds are that you’ll always have some degree of erectile impairment. But we have good drugs now that can get you over that hump.
Beware of claims you may read here and elsewhere about various supplements that can “cure” ED. If there were one, a lot of us with ED might already be stuffing our mattresses with it. Some can help, but only help.