This is Dr. David
I am sorry you are having these symptoms.
it could be a stomach bug or stomach viral infection causing gastroenteritis.
did you have diarrhea on Friday?
this can lead to dehydration if you were not drinking enough fluids.
dehydration can cause headaches and increase risks for kidneys stones or kidney or bladder infections.
it sounds like you need to see your doctor to see if you are dehydrated and if you might be passing a kidney stone or have a urinary or kidney infection.
do you have a GP you can see for these tests?
that is good you are drinking fluids.
gadorade is a bit better to replenish electrolytes.
did your diarrhea symptoms stop?
do you drink coffee? this can sometimes cause headaches.
you you could also cause a sinus infection as well possibly.