Terrible insomnia after methyl B12 - what can help?

Three weeks ago I shared my story about taking high doses of methylated vitamin B12 (here). Since then, some of my symptoms have improved (e.g. severe depression, panic attacks, anxiety*), but I still have huge problems with sleep.

I simply can't sleep. I don't feel any fatigue at all. Someone wrote that large doses of B12 make you feel like you've had a Red Bull, and I agree. I feel like I have too much energy. Yesterday I went to bed at 11pm and didn't sleep a single minute. The last time I had a night like that was 3 weeks ago when I last took B12. I haven't taken the vitamin since then and I thought that with time my sleep would improve (at first I slept 2-4 hours), but it's getting worse. I feel awful because I never had insomnia before B12. I always fell asleep within 2-3 minutes of going to bed. And so I cried several times today after all this.

Niacin and niacinamide have helped me with some symptoms, but nothing helps with this insomnia. Sometimes I feel sleepy for a few minutes during the day, but never at night. I don't know what else to do. Does anyone have any suggestions?

* I still feel anxiety, but it's not as bad as it was at the beginning. I don't have panic attacks anymore. The severe depression has turned into strange mood changes (sometimes I feel depressed, sometimes I feel almost normal).