The feelings you were describing sounds like mood swings which could be a symptom of depression.
I don't really know the exact difference between anxiety and depression but I think anxiety has more to do with fear of something brought on by some trauma and depression are feelings of isolation, hopelessness, etc. Some of the symptoms of anxiety and depression can overlap and be quite similar. I suggest you just "Google" anxiety and depression, you can get a wealth of information from the net.
According to Dr. Gould...
Anxiety often is unrelated to specific events, but is usually caused by harboring some unfinished business with yourself that sometimes comes too close to the surface, and instead of dealing with it directly, you feel afraid of something, which is really dealing with whatever it is...
I like this definition of anxiety.
Anyway, not sure if that helped.
Apparently depression is a disease and anxiety is not; it's something from the past that has come back to haunt us. It's often called the "fight or flight response." You sense something and perhaps think you're in a dangerous situation, so adrenalin gets pumped out and prepares the body for fighting or flight (running), and so on.
Often certain conditions go together and are rarely seen without each other, like depression and co-morbid anxiety. It could be that the anxiety is causing you the depression, as it did in my case. I had severe depression that resembled schizophrenia and was put on a lobotomising medication called Stelazine.
With depression you should just feel "down and out" all the time. Perhaps not wanting to talk to anyone. No enjoyment out of life. Can't do the things you used to do. Don't care about your appearance. Slightest little thing can set you off and you might start crying/sobbing for no reason. There are other symptoms of depression. Essentially you just feel so sad all the time, but it's not just the blues. It's really bad. In the case of bipolar disorder, you'll go up and down ("cycle"). From the depths of despair to elation.
Anxiety is different and often causes rapid heart rate, "jumpiness" (because of the adrenalin rush), sometimes pain, nausea, wanting to escape a situation or the need to leave a situation (like a dinner gathering or something), shaking, and more.
It might be the case that you'll need more time and checkups to "unravel" them if you have both conditions.