I am a little worried because I don't know what to expect
I don't have much advice for you, but I can certainly relate.... I've been diagnosed as Bipolar Type II and my ups-and-downs-and-arounds are completely unpredictable. It is a terribly unsettling way to feel!
I'll give you a piece of advice - I tell this one to myself but I never follow through - maybe you'll have better success? Keep a lot of your mood. Find a tiny little pocket calendar, put it next to your bed, and mark your mood. Beginning and end of day, or middle of day.... Things that you think might be triggering.
Now, this won't apply to everyone here! but I have recently developed PMS signs for the first time in my life :x3: and this situation is encouraging me to finally follow my own advice.
Often, there is no rhyme or reason that I can detect. Sometimes it's chronic pain-related. Sometimes it's how bad were my nightmares the night before (if I slept!) Sometimes it's sleep deprivation. Sometimes it's autoimmune related or depression related or other times more related to anxiety. Sometimes it's all rolled into one confusing ball of garbage.
Wow I'm not making it sound like a good idea, am I? These are all my excuses for not following my own advice. :arghh; I hope you stay more stable than you expect to, but if not, post here and someone will always understand.
It is an EXCELLENT sign that you are catching it early.