What do you think could be wrong?

For the past 2 weeks I have been feeling nauseous, like there is a pit my stomach and it'll just ach.. I have only thrown up a couple times.. I've been getting bad head achs and I'm always tired, and I have to eat ever 2-4 hours other wise I start getting shaky and feel light headed. What do you think could be wrong?Hey I texted Sarah but she left her phone at home.. I got to stop taking naps lol could you tell her that I won't be coming on the count of I over slept by the time I get there it would all be over