Pregnancy or residual period? i experienced what is known as a "one day period"

Had my period for this month (oct) 12-16th. My husband and I of 14 years are trying to concieve. Ovulation was on the 28th of Sept. On the 25th(oct) i experienced what is known as a "one day period" but really only lasted a few hours followed by cramps, nausea ,  fullness in my belly and dizziness which continued until yesterday .  Today I'm just going to the bathroom a lot. Ideas? I'm not due for my next normal period until nov 22nd!