Sorry to hear Tedbear had a bad night. We always worry when Emma suddenly seems worse, but have found that from time to time we have to give her an extra dose of Gabapentin to keep her comfortable. This is usually just a one-off and next day she is back to her normal dose. During the summer I really thought she was deteriorating and we increased the dose for a few weeks but she is now back down to a twice daily dose and better than she has been for some time. Hopefully Tedbear will improve again and this is just a blip.
Nicki - Sorry TedBear is having a rough patch. Of course, you know your dogs best, but is it possible that it's something else besides the SM? Has there been an increase in scratching or other SM signs, or just the restlessness? This can be a really non-specific sign for lots of medical things (or behavioral) and it might be worthwhile to get him checked out for other things just in case. Especially also since the change doesn't seem to correlate to the weather changes as you've experienced in the past, etc.
If Rory is having a rough time (new environment, excitement, etc. seems to worsen his symptoms) I'll give him an extra gabapentin just as needed. I usually don't give 2 at once, but give one and then if he's still scratchy a feww hours later or if he's OK for a while but starts up again before the next dose is due, I just give him another. The timing isn't as critical, I think, as just keeping them comfortable. And likewise - if he's OK, I'll sometimes push the dose back to 10 or 12 hours. As long as he's comfortable, I don't think it matters.