My Vit B12 was so high that it was out of the highest range possible. I'm talking in the thousands plus. My doctor, to my surprise, laughed. I took that to mean it wasn't the end of the world. She suggested that I take my B12 once or twice a week instead of every day.
I showed my sons my results, too (they are both medical doctors) and they told me not to be alarmed either. At 6mos I am slightly anemic as well, but even then, I was told not to be overly concerned. Eat meat. Don't forget to down my iron.
Take your vitamins as directed and it will be okay. I wouldn't say this if I hadn't experienced the same feelings as you did. While it is possible to overdo the fat soluble vitamins (A, D, E, and K), your water soluble vitamins (B and C vitamins) just pass in your urine. It actually takes a long time to get to genuine danger levels.
I have Hashimoto's thyroiditis (an autoimmune disorder). Perhaps you have an undiagnosed thyroid condition. Hypothyroidism is extremely common and is easily treated with medication.
Write to me privately if you want to talk more or if you'd like me to ask one of my sons about any specific lab results. (Not a substitute for your own doctor... just an offer to perhaps ease your mind until you can see someone.)