Groomers seem to be OK (mine never go anyway!), but with them and with vets, you need to tell them to be careful around Ziggy's neck, as that can be a painful area. So no vaccinations or other injections in the back of the neck or along the spine, and at the groomers, no stringing up with a collar. If you don't already walk Ziggy on a harness, it's a good idea to get him one - again, avoiding pressure in the neck area and possible damage to the syrinx.
You can get an App of air pressure for your mobile, but not having a fancy phone, I just use the BBC online weather centre (google BBC and then click on weather, then enter your town). This gives you hourly information about the weather and has one line (at the bottom) that gives the air pressure, so that you can see how it's going to change over the course of a day and for the following 2 days. Normal air pressure is 1010 millibars; it tends to be sudden big jumps up or down that cause the problem with CM/SM dogs - last week, for example, the pressure went up and down by 20-30 millibars on several days, which is a huge leap. The syrinx in the spinal cord and dilated ventricles in the brain both create internal pressure, and if there is then an intensification of pressure from outside as well, you can see why many dogs get uncomfortable. If you can see Ziggy getting affected by air pressure, it helps to give an extra gabapentin - something to OK with your neurologist in January. It helps to make a note of when Ziggy seems uncomfortable and the accompanying air pressure, so that you can show the neurologist the apparent connection.
So glad the gabapentin is making a real difference.
Kate, Oliver and Aled
PS Have just checked tomorrow's weather, which is going to be wet and windy - in my area (Coventry) the air pressure is dropping 33 millibars between 6 am and the following midnight, so don't be surprised if Ziggy is a bit uncomfortable. It's not a sudden relapse, and once the pressure evens out again he should feel better.