Blood testing is important, so if you are concerned about the side
effects, get the vet to do a blood test to assess dosage levels. But, the
side effects CAN continue for several weeks, before they will eventually start to subside. I know it's a hard process - but it has to be gone through - otherwise you will be back at square one.
Don't interfere with the dosing without the vet's authority - and importantly, give the dose at the same time every 12hrs.