I had an IUD (spiral contraceptive device) implanted on the fifth day of my menses. However, my menses normally last 7 days, but after three days from the day I had an IUD implanted, I started bleeding excessively and the [vaginal] blood was smelly, though I was in my 10th day. So, is it permissible to pray while being in this condition?

In the name of Allaah, the Benevolent, the Merciful. All praise is due to Allaah, and peace and blessings be upon the Messenger of Allaah, his family, companions, and those loyal to him. The implanted IUD might lead to an irregular timing of your menses, so if you could recognize the nature of this blood and were certain, or most likely certain that it is menstrual blood, then this blood is considered the blood of menses; therefore, you are not permitted to pray unless this bleeding stops and you become pure (i.e. place of blood is dry or you find no traces of blood). Also, you can visit some female doctors in order to assist the control of this [irregular] blood that comes out excessively and has the smell of menstrual blood. May Allaah increase you in cautiousness and success. And Allaah, the Most High, knows best.