When you had that feeling of complete joy and that everything is great as it is, you were in tune with your higher self. But then you looked at your reality and noticed that the things that you desire are still not there and therefore you became upset about it.
The more you focused on that feeling, the more negative thoughts of others you picked up which brought you down. It is much easier to pick up negative thougths than positive ones and for this reason you got down quicker than it takes for you to become positive again.
I have just recorded depression self-help podcast which might help if you are really down. I have recorded it but I accidentally put the mic sound on very low so I am re-recording it and I will post it as soon as I do that.
This podcast should come up as the first post in this page:
Personal-Development-Blog