I'm caught in a loop

So, I don't know how I ended up here but I guess I'll just do this. I'm scared all the time. I'm scared of myself, and is not that bad because I know I won't end up in an awful place like I used to, but still I get scared that I sabotage myself again. And the most ironic thing is that I believe that this fear is the main cause of this constant imposter voice in my head. So it is like a huge loop I created and I'm not quite sure how to get out of it, everytime things get better for me I get scared, and when that happens I know that I'm going to "relapse" and I'm going to surrender to this imposter syndrome I believe I suffer. I start procrastinating, I don't have enough energy, I start eating unhealthy, I don't feel like doing anything. And then again I hit rock bottom, and all over again things get better, life gets better, I eat healthy again, I feel energized, start studying, I feel motivated but I think you know how it goes by now, the loop repeats itself over and over. This happens very often, it can last two weeks, a month, I don't know it varies but it always happens again. I think it's better than it used to be a few months or years ago, but it keeps happening and honestly I don't know how to stop it or how to deal with it. Things just get to much and I sort of shut down.