Hi Green. I suggest you to write in the Bipolar forum if you want a feedback from people in a similar situation. If your mood changes very often an apparently without a reason it could also be Borderline Personality Disorder, but I'm not very informed about all the symptoms. Hope that people who are experiencing something similar can tell you something more.
It's understandable that you are scared, but to get a dyagnosis is the first step to finding the right treatment and feeling better Wish you all the best.