For a week now I'm getting more and more thirsty every day, drinking 4-5 litres of water and still feeling thirsty, also being light-headed, which gets worse as soon as I stop drinking water. I have also had a cold (or maybe throat infection?) no fever, just sore throat and coughing painful in the chest, as well as fatigue. I have also been feeling hungry all the time. I need to sleep but I keep waking up to either drink water or go to the toilet. I don't know what to do!