Brown

Okay so this cycle was all messed up. So usually i spot 1-2 days b4 AF. However, this month nothing, not even pms symptoms, just tired and emotional. AF comes one day late (usually early, never late) then its medium flow with only back pain and left pelvic light pain, unlike any other AF. 2nd & 3rd day of the same thing with diarrhea and nauseau with some vomiting. 4th day Af is off and on throughout the while day and very light, most of the day didnt wear anything. Today nothing but Brown discharge when i wipe. My cycle is regular, i haven't experienced anything like this before. My cycle usually last 5-6 days long. 1st day light and everyday up until the last meduim -heavy. Last day lighy but still blood red... idk whats wrong with me.. anyone ever experienced this and was pregnant or had something else wrong with them? Or is this normal as well?