I have no idea what is going on.

MESSAGE ME YAZ. I understand!! I go through it all the time, it is from my anxiety constantly. I think you need to take a break and do things for yourself to relax and get back on track. Also with the seasons and everything changing, it IS possible to get seasonal depression. It gets darker earlier, and is darker for longer, therefore you're not getting as much vitamin D, which can also cause things like this. As the person said above, it could also be exhaustion. Running yourself down can make you feel, not yourself.

Awhile ago I went through some serious stuff and once everything got better, I found myself doing a similar thing every night. Everyone would go to bed and I would just stare at the wall because I couldn't think of anything better to do and then I'd just get sad. It happened to me once all the things I needed to take care of every day were done. I didn't have anything else to distract me, so I just kind of shut down. For me it was that I lost track of what made me happy in life. I felt like everything that I had previously viewed as good could just disappear at any time. It all just felt empty. In the end, I had to seek out happiness again and reintegrate the idea that even if the positive things in my life are no 100% guaranteed not to go away/die, that I should appreciate them while they were still around. I have no idea if you had anything traumatic happen that might have caused a similar reaction, but if so, I hope this helps.

Are you going through anything that is giving you a struggle or a recent experience which has shocked you or upset you. Sounds like your unhappy with something in your life, how is work for you and do you socialise with anyone outside work. Do you have anyone you are close to, you could discuss how you are feeling with them and they might have some idea on how you should go about it. try taking up a hobby someway to relieve these feelings maybe jogging or art whatever you like. I find even taking a long walk helps mwhen i feel upupset and when i get a kind of out of body feeling, like i dont know what or who i should be and sometimes i felt like i was controlling a body but with nothing in it. think you need to think deep down if there is anything which you feel is controlling you and make it change. hope any of this helps. you can always talk to your doctor about how your feeling aswell, im sure they would help you solve this. hope you do feel better.

It could be something as simple as just being exhausted. If you are introverted at all, unwinding at the end of a day can seem like a big chore and it's normal. Find ways of just turning yourself off with some you time, watching a movie or reading a book to unwind.

It happens even if I am in the middle of doing the things I mostly enjoy!

I'm pretty sure this is a form of depression. I experience this sometimes (used to be daily when I was younger). Sometimes it was brought on by forgetting to eat actual food, sometimes by hormones being out of whack, but usually I couldn't find a cause. The only thing that brought me out of it was drawing or something. Just doing something with my hands, whether drawing, doing a jigsaw puzzle, or just taking apart an old portable CD player because it didn't work and I found a screwdriver, it made me feel like I was doing something productive and just for me.

If you find something like that, a hobby or just something to occupy you for the night, see if it helps. I don't have any skill with any of the things I did, but it helped so much. Even now, if I notice myself getting back into that same kind of feeling, I'll start drawing or just doodling patterns for my own amusement. Books and video games weren't enough, for whatever reasons.