Stuttering is weird and it wouldn’t surprise me if having started your new job without stuttering put a lot of stress on you. Always hoping you’d be able to keep it up, worrying it would come back, unable to know what to expect every new day. That stress might have finally been too much and is making you have trouble now. Some co-workers likely know since you’ve been stuttering recently, and if they are normal humans they don’t really care. A curse of being a stutterer is that we care a lot more about our stutter than others, but we think that others care as much as we do. They care that you get your work done and don’t make their jobs more difficult. Knowing that they know will hopefully relax you, and in turn allow you to speak more fluently. I say if you want to get it out there to everyone go for it. At the very least there is no anxiety anymore about trying to hide it.