Period after not taking birth control pills?

I got my period Jan. 14 and it lasted for about 6 or 7 days and ended on the 20th or the 21st. I have not taken my pills for a little while ( i know i've missed more than 3 or 4 pills) Then a week after it ended I noticed brown spotting which turned into a red, period-like, flow. I have cramps and feel like im on my period. Is this dangerous? I think I might have ovulated in the time I wasn't taking my pills and my body reacted to the lack of pills and I got my period. Please help, thank you!!