I have been bleeding for 3 weeks now and I got this shot for the first time back in jun and now I feel sick and tired all the time.. what do I do . It won't stop.. the doctor put me on thiis shot to help me gain wietgh and it sucks..? what do I do now when is the bleeding going to stop??

One of the side effects of depo is continuous bleeding. It may or may not diminish over time.

Since this continued this long you need to check with your doctor to see if he would prefer to change your form of birth control as continuous loss of blood can cause an iron deficiency.