3 week long period?!

Kendall • 21 years old and married to my best friend! :D
Ok, so I stopped my birth control about a year ago. I didn't have a period in December or January. Around the end of February my period started and it still hasn't stopped. It's a pretty heavy flow, which was normal for me before I took birth control. I've never had a period this long before and it's scaring me. Anyone ever experienced anything like this? Should I try to go to the doctor? Help I don't know what to do!