we can't make any sort of "educated" guess as to what it is, the best anyone can do is name a drug off the top of their head. your in a much better position to figure out what it is since you have access to the drug in question. if your really curious then get a test kit, this will give you a better idea. there are endless posibilitys, your location matters since there are regional trends in cutting agents. some drugs used to adulterate coke are meth, amphetamines, and rc's which tend to be less common and more difficult to id.
but no body here can tell you any more than that, and thats why these threads aren't allowed.
and to answer your question yes I've gotten speedy coke before. I stopped picking up from that dealer and moved on with my life. if you don't like the coke then dont buy it any more, if you do like it then enjoy.