Question about depo provera.?

My doctor prescribed me depo provera and I got the shot in april my moms friend gave it to me in the buttocks and its had a lump and been bruised in the spot ever since.....is it normal to have some pain at the injection site? Ive also been bleeding non stop on this shot! I go back on tuesday for my second shot. Is it a reliable form of bc my friend was on it for years and loved it she never even used back up protection what do u think????