I'm so sorry, you do sound at your wits end with Archies behaviour.
I don't know about the drugs Archie has been prescribed but maybe you can take a little comfort from our experience with Beau that things can change.
At around 18 months to 2 years old he turned unpredictably nasty, bites coming out of nowhere, aggressively guarding anything and everything, always worse in the evenings. We tried everything we could with no improvement, until we were seriously looking at rehoming as we couldn't trust him near our grand children. As a last resort and after much researching on the internet we decided to try him on a course of a calming/sleeping supplements for human use. We noticed a distinct improvement after a couple of weeks, he was much calmer, the biting stopped and the guarding behaviour much reduced in ferocity. We still carried on with all the conventional training we could as I'm sure this also helped. He has been a different dog, no side effects, just more relaxed and friendly and we can now even leave him alone for the evening with no barking or accidents.
Several months ago we stopped his medication and after a week he snapped again so he's back on it and back to his new normal again.
I haven't mentioned this on the forum before as its very much a personal decision that happens to work for us, but your distress is clear and I just want to reassure you that things can change but you will probably need to give medications time to work properly and continue to look for professional help.