For two days i've felt weak with body aches and headache. diarrhea the first day but is gone now no other symptoms what could i have?

Probably viral: If you are otherwise healthy, by the far the most likely possibility is that you have a viral syndrome. Another is food allergy. If I was seeing you about this in person, I would only be performing other tests if you had other significant medical conditions, had been out of the country recently, or I found something else on exam that was concerning.