Hello! I Am A 17 Year Old Female Who Is

hello! I am a 17 year old female who is sexually active. my last period was normal. this is embarrassing to say, but I was a heavy bleeder. (that is normal for me.) this time around, over the 5 days I was expecting my period, I only was spotting. except on the 2nd and 4th day I had a little more blood. only light though. I'm worried about why this might have occurred. although I am also experiencing sore cramps like I usually do. I just hope you might have an answer for this abnormal change in my body.