What Causes Erectile Dysfunction After A Concussion?

Hi, can I answer your health question? Please type your question here... My boyfriend suffered a concussion during football and ever since can't get an erection. Is this common? Could he treat it with over the counter hormones like Testosterone booster, DHEA, or Nitric Acid? He is embarrassed to tell his parents his problem. So wanted to try before going to them. Thanks