What Could Be Causing A Low-grade Fever For 2 Weeks With Recent Diarrhea, After A Mild Cold?

Hi Doctor, I have been having on and off for few hours a day fever 99-99.5 for past 2 weeks. Last week i had very mild cough and cold which gone now.This week from last 2 days i am having diarrhea with watery stools for 5-6 times a day.I have got covid RT-PCR done twice which came negative.Please suggest.