Do you use internet porn? The major sign of overstimulating your brain with porn - is what you describe - copulatory impotence.
We have seen so many men with this problem, and the "experts" don't have a clue. They don't understand neurobiology of erections, or how Internet porn can alter the brain. So, it's porn, not masturbation that can do this to men.
If it is porn, you need to learn about this condition and about others who have it, and have healed.
Here's the thread you should look at for porn-induced ED. If you control find - "palpateit", you will see my posts. The first 2 posts have links to presentations and articles about porn-induced ED.
http://www.medhelp.org/posts/Mens-Health/22-with-porn-induced-erectile-dysfunction/show/469209