Hi, my 17 1/2 year old son complains of feeling tired a lot. He has some hair loss. He often feels cold especially overnight. He saw the GP last year about his hairloss who did some bloods, slightly low vitamin D, doctor said doing thyroid test but don't know which ones. He has a healthy diet. Works hard at school. Doesn't go out excessively. Has anyone any thoughts what I can go back to the GP with? Thankyou