I'm experiencing insomnia, headaches, cold when others aren't, dizziness, spaciness mentally, and i have darkness under my eyes. what could this be?

Thyroid or Anxiety: It could very well be a disease of your thyroid. It could very well be a form of depression and anxiety. I would advise you that given how extensive the list of your problems is that you get to your family doctor urgently to figure all of this out.

Symptoms: See your doctor to have your thyroid function checked. Also get checked out for the possibility of allergies