We are sorry to hear of your prolonged staining.
Many women experience irregular bleeding with Depo Provera. Unlike other progesterone-only methods of contraception, Depo Provera remains in the system for months, curtailing the options for addressing such staining.
Light brown staining with no hint of a reddish tint does not make a woman niddah or invalidate her clean days, even on a bedikah cloth. But red blood on a bedikah cloth such as you describe, even in small amounts, does make a woman niddah and invalidates the clean days.
Try to clean yourself out well internally and perform a hefsek taharah. Perform one bedikah on day one of the clean days, and one on day seven. (Be careful not to forget day seven.) If these three bedikot are valid, and you do not find stains of a problematic color and size on your white underwear, you can go to the mikveh. In this specific case, the moch dachuk and further bedikot are not required — or recommended.
A bedikah need not be completely clear. Questionable colors, such as brown, should be brought to a halachic authority for evaluation rather than presumed to invalidate the clean days. When asking a question, make sure to mention your Depo Provera injection and difficulties with continuous staining.
Unfortunately, getting into and through the clean days might take some time. If you’re unable to complete the clean days even with the above measures, please get back to us.
Since staining, of different colors, may be ongoing, we also recommend reviewing the laws of stains, as by reading our site’s articles “Stains” and “Toilet Paper“.
You may wish to discuss with your physician the possibility of using hormonal intervention to reduce staining. The section of our website designed for healthcare professionals, Jewish Women’s Health might be of assistance in explaining the implications of continuous staining.
We hope this answer helps you reach the mikveh soon. Please do not hesitate to contact us with any further questions.