My period are always the same. They come at 28 to 30 days, start heavy with very painful cramping and lower back pain enough to make me feel sick. They also last about 4 days. This time my period started 4 days early with none of the usual symptoms. It was very light and only lasted about 2 days. Also the blood was thinner and different then usual. It began with a lot of mucus and then turned stringy and light pink. My boyfriend have been having unprotected sex for around a year now. Could his be implantation bleeding or is my period just acting weird? Oh and I'm 23 years old.