Sick and tired of being sick and tired (TMI WARNING)

So I have been sick now four days. The first day I was nauseous as heck, bad runny stuffy nose (always a problem though I have super bad issues with that. Been told its post nasal drip?) and I chalked it up to just bad stress. Family stuff, a loss, etc. So the whole way home I was like oh God I'm gonna puke. Two hour drive later nothing. So I sit up most of the night waiting to get sick. Doesn't happen so I go to bed just to wake up a few hours later and get sick. Showered, went back to bed. Next day everything aside from my head and nose was fine. I was nervous to eat but ate small things. So yesterday I felt about 95% better so I spent the day out happy to be feeling good right? Went to bed that night with another sour tummy. This morning I wake up and everything is all good. Until I eat some pizza (I know horrible choice after being sick!) two hours later I get the worst diarrhea ever. Literally all liquid. And that's been a thing for like I'd say off and on four hours now. There's a few things I have all this ruled down to. (stress,bad nasal drip mucus crud, or maybe even a lovely preperiod gift from mother nature. I've gotten badly sick before a period before but not a four day event..) I'd love to avoid a trip to the doctor since I never filled out my insurance papers when I was supposed to so it dropped and I cannot afford a visit. Curious though if anyone else has gone through a sickness like this?