HELP! MY PERIOD IS INSANE, IM FREAKING OUT

So period lasted 10 days, which has NEVER happened before. It’s usually 5-6 days and has been for 2 years, and it’s suddenly changing... well it lasted 10 days, stopped for 4 days, and started again with a VERY heavy flow! Idk what’s happening to me!!! I’m on prescription medicine for my skin (acuetane) and have been for 4 months I believe, so idk if that is affecting it. I also take slow Iron pills. I’m so scared, so PLEASE please help me!! I’m also 16