I was feeling the same way for a while, low energy but not quite depressed. I didn't know what was wrong with me but then I had to go into IP because things weren't getting better. The doctors told me I was in a depressive episode even without the mood being present. Even when I got out of IP I was still feeling weird, honestly I probably should've been in there longer, but I hate being in there. It's gotten a bit better now that I made some changes to my daily routine and started pushing myself harder to get out of bed and do things, even if it's only doing one load of laundry, which is a mountain of a task since I let it pile up so much in the depressive episode. Now I'm having a mixed episode though, grrr.

I really hope you get to feeling better soon!! You can try doing one small task a day until your energy returns, I can't say that it's going to make you feel back at 100% but it can help fight the low energy.