I get this too. For the longest time I thought it was my work pager going off. I also have bugs crawling across my foot and cold water dripping on my foot and leg. All of these symptoms were before my spinal cord stimulator so it is not related to that. The dr. just said, "It's probably related to your arachnoiditis."

The buzzing is weird but doesn't hurt me either.

I get this too sometimes, the first time it happened I was standing on the pavement over a basement I asked my husband what the buzzing was under our feet, he looked at me blankly, I moved him where I was standing and expected him to know what I meant, he said there is nothing there, then I realised it was still happening and it was me, as you say no pain just something I have to put up with.

I know just what you mean about the bugs crawling on me. I don't get that nearly so often since my lumbar fusion.
I used to get it particularly up my left leg on the outer calf. One day I was in a friend's garden having coffee and she told me I had a spider crawling on my right leg. I laughed! I could feel it, but just thought it was a nerve symptom!