Suggest Treatment For Irregular Menstruation

Hi, I just had a few questions about my body. Okay, well this month my body has been abnormal to me. I was originally supposed to get my period on April 28th but did not recieve it until may 4th. Then my period was not regular at all, it was heavy the first and second day and then brown blood the third day, after that I started spotting light pink for the next four days. Usually my period is 5 days at most so I didn't really think anything of it. I did have unprotected sex on May 2nd but thought I was fine because my period arrived two days later. My period is now off and for the last three days I have been feeling sick and been extremely tired. I find myself dosing off at work and even when I drive sometimes. Do you know what may be happening with my body right now?