The first thing to check is whether you can clear -- if you do the nose-pinch Valsalva thing, can you feel air going into both ears? If so, it is probably okay for you to dive, but what you want to avoid is the problem that caused the full feeling in the first place.
What happens when you equalize too late, is that tissue fluid exudes into the middle ear space. This can be cumulative over days, as Judy describes. If the acute injury is severe, you can actually get bleeding into the middle ear space, and in the drum. This can look very much like infection to a physician who is not familiar with barotrauma.
If barotrauma is bad enough, it will make it difficult or impossible to get air through the Eustachian tube in order to equalize pressure. If you find that, on your next attempt to dive, you are really having to honk to equalize, you need to abort and give your ears some time.
People are frequently (really, almost universally) confused about barotrauma, middle ear infection, and outer ear infection. They have different symptoms and different treatments (and different prevention).
HERE is a small essay I wrote about it, in an effort to make things a bit clearer.