Welcome D-rule. I see you've posted many times before, but I think this may be your first time in this particular forum. I hope we can help you.
Bipolar is definitely long-term, and can be managed rather than cured. It can be set off by an event (a trigger), but the cause is believed to be chemical and/or genetic. I.e. if you don't have a predisposition to it, an event won't trigger it.
Your mood swings sound rather rapid to me. -- How many do you get in, say, a month? You could have a form of bipolar with rapid cycling, but bp is often confused with other things, and it could just as easily be something else going on -- or even your meds (I know some people don't react well to Prozac). When did you start noticing the swings?
You should have a look at the "Bipolar Recources" thread second from the top of the listings for this forum (grey shaded area), and you might also find the following summary informative: http://www.dbsalliance.org/info/bipolar.html
Your best bet is to see a psychiatrist to get evaluated. You cannot diagnose yourself with this, and nobody here will be able to do that for you either. If it's not bipolar, they will be able to help you with what it actually is. General docs aren't really equipped to handle bp in terms of expertise or the amount of time they can give to diagnosis, monitoring, etc.