it sounds like either its contaminated, its dosed way too high, or its got too much BA.
all of those can be fixed.
first off, lets try to bake this, or put in boiling water. this is to evaporate the BA if theres too much BA. after that you need to add in BA so your gear will have 2-5% BA. id go with 3.5%. (to fgure out how much BA to add to make it correct % youll need to do a bit of simple math).
now what you have is a sterilized gear with a small percentage of BA. if you inject this and it still hurts, then you know it wasnt that your gear was contaminated OR that it had to high BA, but that its dosed too high. if your gera is dosed to high, you "cut it" by adding in some sterile oil. this dilutes the concentration of deca in the gear and will take away the pain.