Hello, as per your question fever since one week along with headache and stool disturbance, most probably signifies to the typhoid fever, however it can be due to malaria or other causes, if the Fever is increasing then decreasing and again increasing, go to the widal test for typhoid to rule out the cause
Next Steps
Get a cbc with ps for comment done
Get a widal test done if one week has gone
Get a ps for malarial parasite done