I've never used omeprazole so can't help on dosage, but if Charlie is showing signs of pain then you need to keep on with the gabapentin. Omeprazole and cimetadine are diuretics - they reduce the level of fluid in the body generally, and for CM/SM purposes, reduce the level of cerebral spinal fluid in the skull. This will reduce the risk of syrinxes forming and if the dog has dilated ventricles can reduce the pain these cause. But most of the pain displayed will only be affected by gabapentin, because it is specific for neurological pain - which ordinary painkillers don't help. And it is important to give gabapentin regularly so that it provides 'blanket coverage'; it is a pain suppressant, rather than an occasional painkiller. The immediate positive effect of gabapentin is sometimes taken as evidence that CM/SM is present, because it won't work on non-neurological pain such as arthritis, but can often have a quick and obvious effect on CM/SM pain.

Kate, Oliver and Aled