Can your serotonin levels drop?

For a few weeks after I got out of school, I was only getting 2-4 hours of sleep, mostly during the day. I also got sick and stopped eating for a few days. After which, I noticed that I began showing symptoms of low Serotonin levels (sinful thoughts that cause me a lot of regret, obsessive thoughts, no desire to go out of my house, etc). I have begun sleeping at night and longer, as well as eating (since I'm not sick anymore) and have noticed I'm getting better mentally. I was just wondering though if those issues may have caused my serotonin levels to drop down too low and if they'll ever get back to normal. I was also wondering if masturbation may be an issue, since I stopped right around the time I stopped eating and sleeping, although, I've gone days without it before. Could everything happening all at once caused the drop? Just please say I'll go back to normal soon, the obsessive thoughts are killing me. Thanks!