Based on details you had acute enteritis
( diarrhoea) and now you have headache.
Headache and generalized weakness can be due to decrease sleep.
Have plenty of fluids especially electrolyte solution /ORS as per loss.
However if headache is persistent and worrisome, you need to consult Neurologist
for clinical examination , need to rule out cerebral sinus venous thrombosis
secondary to diarrhoea and dehydration