Hi there and a very warm welcome to Hub Pages.
I wouldn't worry about the hub score going up and down. I've published 40+ hubs and have been here for over a year and my hub score still goes up and down like a yoyo! I also make comments, hub hop and so on, but it can still go down a few points and then it goes back up again.
I think as well, with me at least, the hub scores seem to be behind a day or more. For example, I've maybe been on Hub Pages doing a lot of activity on a Monday and Tuesday, not so much on Wednesday or Thursday. My hub score doesn't go up on the Monday or Tuesday, but shoots up on the Thursday and back down on the Friday??? Why it works like this I have no idea. But just keep on doing what you are doing - questions, following, hub-hopping, commenting etc. and your score will steadily go up even if it slides back one or two points.