I've almost completely lost my sex drive?

I'm a 17 year old male. I used to masturbate about 3 times a day (a little high, I know) And that number started declining sometime late April. It was down to once a day by the end of May and down to once every other day around the middle of June. I then lost my virginity in the middle of June (to a girl I met after the decline started... we all make mistakes). I wasn't able to climax with her despite keeping at it for over a half hour, and since that experience I have yet to even have an erection, even if I try masturbating. It's been almost four days and I haven't even had an erection. I used to get about 15-20 a day! What's happened and will it come back?