Serious question!

I started AF 9/5. 4 days before that I was experiencing nausea. Now while on AF I'm still nauseous during the day, once at night it dies down. I had to take a nausea pill this morning so I can be able to get up and walk around, well it took the nausea away but still left me feeling weak. Has this happened to anyone and what was it? pregnancy although AF came or something else? I'm drinking lots of water to keep myself hydrated.