period

okay so i’ve had sex with my boyfriend multiple times before. its always been protected sex, but im not on bc. the last time we had sex was before my last period. it was late, but it still came. it was a lot lighter than my period normally is, but it lasted the time as my period normally does. i have an app that tracks it, but those aren’t always accurate. it said my period was supposed to come in 6 days, but last night it came along with really really bad cramps. its heavy when i have a tampon in, but when i go to take it out to switch it, it’s a light flow. should i be concerned or is this normal?