My son aged 8 is complaining of the following symptoms the last 2-3 weeks. Excessive tiredness, fatigue , pains in legs and feet . Excessive thirst, using the bathroom to pass urine, or he is constipated/diarrhoea. Hungry a lot of the time, complaining of pains in his tummy too, and pain around his bladder area, although urine clear. Headaches and clammy at times. Any ideas what could be causing this?