Some people experiences "up" episodes where they feel unusually happy, energetic, agitated, etc but not to the degree where they are manic. These episodes are called hypomanic episodes. Hypomania has symptoms much in common to mania, but to a milder degree. Bipolar I subtypes experience both depression and mania, whereas people with Bipolar II experience depression and hypomania.

It's also possible to have depression that cycles. Some people believe that cycling depression could represent a "Bipolar Spectrum" condition where their "highs" are represented by periods of normalcy. The bipolar spectrum may also include depression cycling with anxiety. My psychiatrist has suggested to me before that my fluctuating states of depression and anxiety could be a manifestation of bipolar where my anxiety represents the "highs."

I don't even know why I'm wasting your time writing about this when you can check out this website: http://www.psycheducation.org/depres...diagnosis.html
Read this! This is a fantastic website. Even if you're not on the bipolar spectrum, you should find helpful information here.

Also, hypothyroidism is often tied with depression, and hyperthyroidism with anxiety. There's the chance your thyroid could very well be influencing how you feel!

I hope this helps.
But please don't self-diagnose or allow someone online to suggest a diagnosis for you! I am just providing you with information. It's important that you visit a physician, therapist, or psychiatrist to really get an idea of what your experience is.