This has never happened before and I feel awful. It hurts him because he's afraid I've lost interest in him. I've tried everything I can think of and can't seem to make it work. I'm pretty freaked out. When something happens that's never been a problem before, it's natural to be upset and imagine the worst.
Many men have occasional periods of impotence.
However, few men feel comfortable talking about impotence, so it's easy to feel like you're the only one when it happens to you. Find a good physician and have yourself thoroughly checked out for possible medical causes. There are all kinds of possibilities. Impotence is a side effect of some medications. If the impotence is not due to a medical problem, then find a good psychotherapist.