What Causes Irregular Period With Frequent Urination?

I always have a regular period, about a 30 day cycle and know about a day or two before i have it that it is coming. It usually lasts around 4 days. I had my period on August 8th and then started bleeding again around the 28th of August. The bleeding only lasted 1 1/2 to 2 days and i had no idea it was coming. My fiance and I have unprotected sex all the time because he had his sperm count tested a few years back and it was very low so I figured the chances of getting pregnant were very very low. Ive had weird appetites, feel sick after eating, frequent urination, constipation, and am constantly tired which is very unlike me ..it literally feels like something is sucking the life out of me! Ive also been very emotional, crying over just about everything. Could i possibly be pregnant? Or does this just sound like an irregular period?