welcome to the forum, Bezzy. I'm sorry you are struggling with this flare and I hope you will find good support here.
I think you are going to have to expect a longer process to remission. One week on SCD is not sufficient by a long shot.
How long have you been on pred at 40 mg? You might need a higher dose to get this flare under control, or you might just have to wait it out. You should have some improvement after a week on pred, but total remission might take several weeks. You might consider a completely liquid replacement diet to get to a quicker remission - some here use Ensure, others recommend the prescription nutritional drinks because they have less sugar.
In the future, most of us here would recommend that you continue taking your meds during remission to prevent flares.