After Two Days In Cancun Mexico, At A 4 Star

After two days in Cancun Mexico, at a 4 star resort, I exhibited the following symptoms in the order noted.
Day 1 - Chills and Night Sweats - probably fever, although I didn't check
Day 2 - General Malaise, Coughing
Day 3 - Loss of Appetite and Diarrhea
Also possibly relevant, is that a co-worker reported chills/fever prior to my departure to Mexico.
The question is whether it is more likely that a have a bacterial infection that I picked up in Mexico, and thus need to treat with antibiotics, or is it more likely that I have a virus - in which case I should just wait....