MrCuddly
You may never know the root cause, or may only find out after you've peeled back the onion a bit knocking problems of your list. But who cares, as long as you get back to normal?
Iodine and mineral supplementation can help with low thyroid, adrenals (some would even argue heavy metal detox). Colon cleansing helps with a variety of symptoms too that could hold you back no matter what else you're doing right.
Of course diet is the big variable "let your medicine be your food and your food be your medicine". Juicing, more raw foods and superfoods in your diet, less processed foods, etc.
Personally I would start immediately with:
1)
Iodine mineral supplementation to get your thyroid function back to normal - 2) detox with a colon cleanse
3) a super foods and nutrient dense diet.