What does this mean!!! im scared?

ok well every since last saturday ive been rlly scik...well not rlly scik but like my tummy would hurt and then i would feel the vomit coming uo my throut but i would nvr get sick...it mostly happens after i eat and at night. also im always burping and gy. and i have to pee constatnly...i want to know what this means cause im scared...its been 8 days since it stared but it wasnt as bad as when it started. it slowly go better. i even triend a pregnacy test,... but i nvr had b4. ik rlly scared and want this to go away. my school nurse told me to get lots of sleep and drink lots of water...wheni drink water i feel sick and i cant sleep cuz i feel to sick to!!!! what do i do!!!