What Causes Headaches, Dizziness And Tiredness After Using Depo-Provera Injection?

hi i had a deo-provera injection 2 and a 1/2 mths ago ive been suffering with severe headaches,dizzyness,and tiredness ive been like it for 2 mths now n painkillers dnt seem 2 b wrkin at al,
this isnt the 1st time ive used this injection i started using it wen i was 15yrs old and was on it for 3yrs, im confused as i neva felt like this on it then, i would of stopped using it if i was plzzzz help thnx.