Hi Jacki, those are extremely important questions! So for anyone who has a question about whether it's gas - If you don't know, then off to the vet ya go!
Gi Stasis is always a symptom of something else. Too many carbs, something digested that's not easily digested, not enough fiber, an illness, bloat/gas, stress, pain etc.
So IF the onset of the gas is quick and I notice it right away, then I offer simethicone (for babies - like "Little Tummys) and a light tummy massage first.
However, both my husband and i work from our home office, and we see our bunnies all the time, so we are able to spot a problem quickly. I know others may not have that luxury. If I had no idea for how long it had been going on or if they seemed lethargic, I would be off to the emergency vet.
The symptoms of gas include an uncomfortable sitting position, a tight bloated tummy (but not always),sometimes grinding of teeth due to painful gas, very loud gurgling noises (where you can hear it clearly just sitting next to your bunny). Then I watch carefully for the next two hours. So far, this has solved both Bailey & Rucy's bouts of gas over the years.
It is important to note that if the symptoms of gas do not go away within a a couple of hours then a rabbit can go into shock if in severe pain and/or full blown gi stasis can happen due to the stress of less severe pain.