I can't speak

I am not, nor have I ever been, a big speaker. Probably it's cause I don't have all that much to say. But lately I can not even make myself understood when talking to a group of people. At work today I tried to explain why we do a specific thing the way we do, simply to avoid mistakes. Since people didn't know this they did not do the specific thing correctly and hence mistakes were made. It was a simple fucking thing to explain, but all the words came out jumbled and incomprehensible. Not a great feeling.