Hi. First, it was unwise to administer this drug without veterinarian supervision, not least because the tablets will be completely out of date and changes may have occurred to the drug itself over this period of time.
A gradual reduction in prednisolone dosage gives your dog's adrenal glands time to resume their normal function. Failure to taper the dosage down over several days or weeks (according to dosages and times being given) can cause withdrawal effects including lethargy, the inability to digest food, vomiting and difficulty in breathing.
It is for the above reasons I strongly suggest you contact your vet, explain that you have started using the prednisolone you had left over from last year and ask about a new part-prescription, so you can taper off properly and slowly. The amount of tablets you have left are insufficient for safe withdrawal, so you will need a few more from the vet.
I am in the middle of a three day course for a inflamed esophagus which is hindering my breathing I have to take 50 mg a day then stop,doc said if its only for these 3 days it wont affect me in that short time.
Was on 15mg of preds a day for 2 years for polymyalgia took me months to come off them so it worried me to go on this high dose and stop cold turkey.
Dont know if its the same for a dog as the preds are quite a powerful medication.
Yes you must check with your vet as soon as possible,also try Malaseb medicated shampoo it has no equal for most rash and its magic on hot spots and any nasty rashes, expensive from vets but good price on Ebay and very safe.