My periods have never been this short they always last a week

I had my period last month on the 18th and it lasted all week they usually do, but this week I started on the 16th an it lasted 2 day it was heavy not as usual but it was still heavy an by the 3 day I'm spotting very lite pink blood like its almost gone. I've been having breast pain for 3 weeks headaches for 3 weeks and cramping. Could I be pregnant. If not could someone help me and tell me what they think is going on....????? O ya my periods have never been this short they always last a week 6 day if I'm lucky and there all was on track but these one started a couple day early an now it's gone????? HELP Please