Your penis needs time to recover from the first ejaculation. Depending on your age, when you first start having sex, you can "get it up" in as short as another 10 or 15 minutes. Later in life, in your 30's, it may take an hour or so. It all depends.
Well there are medicines out there that you can take...how well they work, I don't know. But don't consider yourself an outcast or anything b/c of it. There are quite a few guys out there with the same problem.