I have been having irregular bleeding for a few months due to taking an injection called Depo-Provera (a form of contraception). I think most of the time this blood came out when doing ghusl. I just found out that anything that comes out of the rear during ghusl nulifies wudu. I didn't know this and I did my salah after taking proper ghusl without renewing my wudu (as blood came out during ghusl). My question is do I have to repeat all those salah that I did after ghusl without renewing my wudu (most of them were fajr prayer and I don't clearly remember which other prayers I performed in this state)?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

If your bleeding is continuous in such a way that you do not have enough time to perform the prayer during the time of the prayer (from the time it begins until the time it ends), then you should perform ablution immediately after the time of the prayer commences and pray with this ablution the obligatory prayer along with any supererogatory prayers that you wish. However, if your bleeding ceases for a time that is enough for performing ablution and the obligatory prayer, then you are obliged to wait for this time when your bleeding stops and then pray during it. For more benefit, please refer to Fatwa 99890.

If you did not perform ablution out of ignorance of the ruling when you were obliged to do so, then there is a difference of opinion in regard to whether or not you are obliged to make up the prayers performed without ablution. Most scholars are of the view that you are obliged to make up your prayers.

The method of making up those prayers is that you should endeavor to estimate the number of prayers that you had prayed in that condition, and then make them up all until you are sure that you are free of liability.

However, some scholars, like Shaykhul Islam Ibn Taymiyyah are of the view that you are not obliged to make up the prayers due to your ignorance of the ruling. But the view of the majority of the scholars is more prudent and more hopeful of clearing one's liability.

Allaah Knows best.