I left work early because i wasn't feeling well. tummy and head feel weird. check temp its been 99-99.2 is this a low grade fever or the start?

Depends on person: Fever is defined as a body temperature of 100.4 F or greater; however, some people run low body temperatures at baseline and in these people a temp > 99 might represent a low grade fever. In general, adults are not as likely to have a fever with infections than children. You know you are not feeling well, and that can actually be more important than the thermometer reading. Tylenol (acetaminophen) may help.