Heavy flow

So my daughter (she is 11 years old) got her first period last year on December. At first she was regular but then it began to be irregular. I read that sometimes at the beginning, irregular periods could happened. It also runs in my family including me. There will be times that I won’t have a period for two to three months. Well my daughter hasn’t gotten her period for two months until yesterday and I noticed today that it’s really heavy because she showed me her pad. She also has been passing some clots. Should I be concerned? She is not complaining of any pain. I don’t know if I’m overreacting because my period are so light that there are times that I don’t need to where a pad but I do maybe put a thin panty liner just in case but I do remember my periods being so painfully horrible when I was a young. What you think?