^^ don't let it drag you down. I can empathize a lot, may it be depression, self-doubt or -loathing, craving etc. Often when I experience these feelings after some time I feel like "WTF happened??? That same old feeling is back, so fuck it, I'll go fuck myself up. Everything is so pointless!" or even feel guilty for it like I had done something wrong to deserve feeling like shit.
When I was in detox, a woman in my therapy group was bitching about how she couldn't sleep and felt awful all the time day in day out. It was a bit exhausting for everyone in the group. Then a therapist said something I that made me really angry at first: "Please stop complaining all the time. It doesn't make anything better, and in the end you don't have a right or sth. to be well and happy all the time. " I felt offended by this and thought "How can she dare? She has no idea what we are going through. That's so brutal." But halfway through rehab I understood the meaning of that. When I feel bad that does not necessarily mean that I or someone else did something wrong and it doesn't mean that life is unjust. It simply is life, you feel bad sometimes and you feel good sometimes.
It helped me a lot to take a step back and watch myself. Are there possible reasons or triggers for that? How do I behave when I feel bad? Is that behaviour functional? And how does this crazy space monkey I call me behave this time ;-). That takes the edge of it for me.
I whish you a lot of power to go through that! If you like you can always drop me a pm!