Hello, I Have Not Been Feeling My Best No One

hello,
I have not been feeling my best no one thing is exactly wrong I would say however, i have been very tired lately in fact very tired almost falling asleep while driving. At random times i become nauseous, i have had excessive gas and random back and abdomen sharp pains. I have also had moment of acid reflux or just a feeling directly in the middle of my chest. I have taken 3 pregnancy test and i don't really think its that at all.