What Causes Continuous Periods For Long Time?

i have been on my period for 3 months..i havent went to the doctor or told my mom because i was too scared..i dont want to get an exam because people say it is an unbearable pain. the past two periods have been 2 to 3 months long. i have had a lot of anxiety,peer pressure, fatique etc. that may be the cause of it..but im not sure.. my periods have been normal since the fifth grade but now they have been abnormal the past couple of months..so what do i need to do..?