It could be a mixed episode. Have you been formally diagnosed with bipolar disorder yet? I ask because it's generally not a good idea to treat bipolar with an antidepressant alone, as it can lead to mania or mixed episodes. I try to stay away from antidepressants altogether but a lot of people can be on them with the help of a mood stabilizer. Having all the energy of a hypo/manic episode but the thoughts/feelings of depression usually constitutes mixed for me. That's the worst place for me to be. It's the most uncomfortable.