what you are having is basically co2 poisoning. you are smoking either too long (4hour + sessions) or too much under a short period of time, it also can be your hole placement so are you doing anything special with your holes? you can try eating so you dont get the hookah headache as bad but if its co2 poisoning then it wont matter if you eat. smoke outside in a well ventilated area to help with this or do not take as many puffs in a short period of time, take a few breaths between puffs and dont rather than breath oxygen breath smoke through your hookah. if your hole placement is bad then it wont matter how often you take a puff depending on a few factors.
i used to put holes directly under my coals and this gave me lots of thick smoke but it also gave LOTS of co2 and i would get nauseous, cold and clammy, lack of energy, and a horrible headache in that order. please be aware if you at any time begin to feel drowsy while smoking immediatly stop smoking and head outside. this is a sign of co2 poisoning and it can lead to your death. it is caused because co2's bind is stronger than oxygen to your bloods hemoglobin so co2 stays longer to blood so you get less oxygen.
to put it in a simple sorta thing you can imagine (the following things said are not actual numbers but just an example) every breath you get 100% oxygen and when you get to 30% oxygen per breath you die due to asphyxiation (thats not good as pure oxygen is toxic). every time you take one puff off a hookah you get 1% less so after 10 puffs you now get 90% oxygen per breath. it takes 5 regular breaths to get an increase of 1% oxygen so if you take 10 puffs of (this isnt very simple now hahahahaha) your hookah it will take you 50 regular breaths to get back to 100% oxygen per breath. keep in mind the actual number needed to get that increase in percentage is higher. when you get to 80% you get nauseous, when you get to 60% you get a horrible headache, when you get to 50% you get cold and clammy, when you get to 40% you get sleepy and down to 30% you die