If you're having erection problems, the most sensible thing to do is to consult a urologist. ED is a multifactorial condition and you need to do a series of tests to determine the exact cause of your problem (psychogenic, vasculogenic, etc). Only then will you be able to get the right treatment. Most of the products you see on the Internet are useless and some may actually do you more harm than good. So, my advice is: don't risk your health, don't waste your money and go see a urologist.
Do not be too alarm my friend. Not staying erect does not mean that it is forever.
Listen to your body. Take notes on how it has changed prior to your problem. Was it due to stress, sudden change of diet, smoking?
I have a friend who used to smoke. When he switch to another brand of cigarettes, he found that he had erectile dysfunction problem.