When my child was 3 months old I asked a question about her then-terrible sleep. While she has never developed into a wonder sleeper her sleep has gone from abnormally-bad to generally good. As I worked on her sleep I learned the many causes of her issues at the time. Would it be appropriate to answer the question with an update as to what caused her issues? It turned out that none of the existing answers, on their own at least, helped.
Yes, sure, feel absolutely free to post and accept your own answer if you have knowledge to share. In fact, we encourage this on all Stack Exchange sites. Don't feel as if you are slighting the answers that were posted, you're providing useful information for those that happen upon the same problem that you had and your insight and experience might mean that someone else has an easier time.
Don't forget to vote for answers that helped a bit, but be sure that you accept the answer that helped you the most - in this case, it would happen to be your own. You can provide comments on what parts of the other answers were the useful ones. In your own (accepted) answer, consider mentioning why you answer your own question - that removes all doubt.