flu/company advice

yesterday i went to my little sisters birthday, a millllllion people were there. from age 1 to age about 90. i felt tired and my muscles kept getting tired just from standing.
i havent had a day off in a while and to be honest that many people really drains me so i didnt think much of it. well i got home, feeling a little nauseous like bloated and that...stagnant feeling in my stomach. thinking about it i remembered i went to dennys earlier this week and my friend ate some of my milkshake. a few days later at work she is telling my all these symptoms (thowing up, diarreah, soreness..etc...). im like...Dude-you have the flu. she said "wow really?*coughcough*" and she never covered her mouth either  

anyway....
im not sure if what i have is the beginning of the flu or just fatigue and nausea from bc (not uncommon for me) but my brother was suppsed to come over today for dinner with his family, and im supposed to bring a plate over for my gramma. i dont want to get anyone sick, i especially would feel bad if any of the babies or older ladies at the party yesterday get sick because of me  

would you cancel guests and stuff? fatigue, bloat/nausea are the only symptoms so far. my mind is kinda swimmy and ears are kinda ringing too. just like, my head is blah. I took my temp and it was 98.0.