Hypothyroidism, does eating sugar make symptoms worse or am I diagnosed incorrectly?

I have been to a doctor who really can't find what is wrong with me. He thinks its either candida or hypothyroidism. 9 months ago I took a drug called mephedrone, and since then haven't felt the same since. I can't eat sugars or grains really without feeling really woozy and spacey. I also have really red itchy eyes, mucus under my eyes, massive fatigue, digestion problems, really dry skin, and difficulty thinking straight, I mean I can barely type this out too due to all the mistakes. I took diflucan for about two months now and haven't really noticed a huge improvement. I still have all the problems, maybe slightly better. I have completely changed my diet since I have seen him and I think that maybe has helped. I think I have felt some die off symptoms, but I don't know, could actually be me worsening something. The reason he suspects it could be hypothyroidism, or just plain something wrong with my thyroid, is because I had told them that for as long as I can remember I have had dry skin. I also have alopecia (sp?) and have had that since about third grade. I don't believe that taking a synthetic drug could cause a candida outbreak or cause all the symptoms to flourish, but I'm not a doctor. Could someone please give me some additional insight?