It's quite common for stutter to vary over time like that. I can have days - or even just periods within a day - where I stutter a lot, and then not long after, there won't be much left of it. Some periods stretch longer than others - e.g. I've had a long stretch of a problem with 's', which does seem to have resided a bit now. Just know that this is how stuttering can be, and maybe it won't feel so bad for you. Frustration can lead to more stuttering, I think. It's this whole "simmering" mess...