Runaway Shame?

I made another realization recently. When I am depressed, I don’t know what makes me sad, but I feel sad (it’s worse than “sad” but that’s the general family). I imagine that when people get panic disorder they fear fear for “no reason”. So, I was thinking – perhaps depression is when sadness goes haywire, panic when fear goes haywire and BPD (or ERD, or whatever the disorder is called) is when shame goes haywire. It’s not like there is a “valid external reason” to feel shame. They just DO. But often they look for external reasons. It’s a theory anyway…