Sounds like you're equating airlock bubbles with being a fermentation gauge, and not going by gravity, so you really don't know what's going on.
How do you know if it's fermenting rather than the airlock just bubbling? An airlock is a vent, it's NOT a fermentation gauge.
It could just as easily be bubbling or stop bubbling for that matter, due to changes in barometric pressure, temperature, or whether or not the cat or vacuum cleaner bumped into it, as it could be to because it's still fermenting.
Activity, action, bubbles, even krausen can be affected by the envoironment just as much as it being caused by the yeast...so going by that is NOT reliable.
If you want to know what's going on with your beer, then take a gravity reading. The only way to truly know what is going on in your fermenter is with
your hydrometer. Like I said here in my blog, which I encourage you to read,
Think evaluation before action you sure as HELL wouldn't want a doctor to start cutting on you unless he used the proper diagnostic instuments like x-rays first, right? You wouldn't want him to just take a look in your eyes briefly and say "I'm cutting into your chest first thing in the morning." You would want them to use the right
diagnostic tools before the slice and dice, right? You'd cry malpractice, I would hope, if they didn't say they were sending you for an MRI and other things before going in....
Counting bubbles does not equate to anything usable in fermentation. It's not like "x bubbles/minute= y gravity points." It just means that co2 is being released....but it could also NOT be bubbling, and still fermenting away.