what does it mean when your periods are 4 days and in between mine went from 36 to 40 apart

hi im 24 years old my name is Denise and i have a problem and i have had it for over 15 years when i was in high school i got this arm implant in and i had it in for about 2 weeks and then i was getting very painfull pains in my stomach and i went back to the doctor and he said it was just period pain so i left and then the pain got worse so i went to another doctor and he said i needed to get it out so i got it out and then had problems i started to not get my periods for months and then i had a phantom pregnancy and the they came back 4 days and in between it went from 36 to 40 days a part so can anyone help me please if anyone has had the same problem tell me please i want to know whats going on