Cause of endless cycles of depression?

About once every 5 days to a few weeks a depression from hell hits like a tsunami. What could cause that? It gets so bad that I move like a snail like a person does when they have a really bad flu or like I'm 100 years old. I feel an ache in my soul that's indescribable.

All I know is that I can't do this much longer. It's getting worse. I have no idea what's causing it. When the depressive part of the cycle ends I get hope and somehow convince myself I won't let myself get depressed and suicidal but sure enough I change into a completely different person and get extremely depressed and start doing suicidal planning. It's just horrible. It has a terrible effect on my body, which aches for days after it ends. The only good part is that I sleep like a rock for a long time while my body heals.

None of my psychologist ever told me what's causing it. She had me do a cat scan which didn't show anything so it must be psychological. I was diagnosed with a lot of disorders but the only one that has cycles seems to be BPD, but I don't know if BPD is known to cause such endless horrible cycles. I was also diagnosed with DID by another psychologist but I don't know if that could cause this.

I took DBT and EMDR but it didn't seem to help me.

Any ideas?

I am so sorry for your pain.

I take 3 antidepressants just to keep going... it's hard.

Hugs, if wanted.

I'm not sure about the cause. Maybe someone else might have some ideas. I'm so sorry for your pain.

Are there any external stressors you can pinpoint? That could be the BPD if that's a yes. Is there any correlation between when these depressions hit and how you're eating and/or sleeping? It could be just a need for rest catching up to you too, a lack of sleep can really, really throw us out of whack. How long do these depressions last?

Good questions. I'm easily triggered and know that causes bad SI depression but a lot of times it feels like I change to a different person and then I know the inevitable bad cycle will start within a day. The depression, SI and planning usually last 2 to 5 days. Yes sleep definitely helps, always. Sleep is magical!