hi,
years ago i was diagnosed severly depressed but it was not until this year i was diagnosed with bipolar II with psychosis. i believe it is possible that bipolar stems from depression. the net is a good way to research this and also speaking to your doctor. it is also possbile to build up tolerance to certain meds; so you might just need to increase your dosage. i'm on zoloft and risperdal; they both work together and my racing thoughts decreased significantly. hope to hear you are doing better.
gwen