Hi Leo,
Thats such a positive update, well done!
We are dealing with our own problematic Cocker - what kind of things did you do? He seems to be in a bit of a bad patch at the moment, a bit more snappy / guardy / anxious than he has been the last few months.
Feels like we take one step forward and 2 back sometimes. We've worked with 3 different trainers, none have been particually insightful!
Oh bless you, I think it's natural to always have some setbacks.
We tend to find our own lives affect the way Leo responds so if he ever reverts to old behaviours I take a step back and look at what might be going on in our lives to cause him anxiety. (a big trigger for us is my partner going away, he's military so leo has become quite anxious even if my partner packs a rucksack. Let alone goes away for a single night). And if he ever reverts back to his old ways, I too revert right back to basics in terms of training as well, I never see it as a failure if I have to take him back to basics and do things I would have done a year ago, in fact Leo seems to be relieved if I do.
In terms of snapping, aggressive behaviour, I have invested a lot of time into reading Leo's body language and using a hands off approach. Leo is never handled unnessessarily, for example, if I need him to move away from an area, I call him away and make a different area look really appealing. If Leo lunges at me for any reason I use complete ignorance. Numerous times Leo has physically hurt me in the past, I tried to follow the good old tactic of shouting ouch! Or yelping, to which I have found Leo just gets even more excited. So now I just stay as silent as I can possibly stay and when he dosnt lunge again I will just stand and tell him 'back!' with a stern finger point and he will generally oblige. Ofcourse he dosnt follow this to the text book and pushes his luck but I cannot endorse using a hands off approach enough. We are at a point now that aside from getting s little over excited in playtime, Leo dosnt feel the need to snap at me in any incidence, however it's taken me nearly 3 years to build this trust, and with others he will still feel to anxious to be handled.
I was reflecting with my trainer the other day about how far Leo had come and she reminded me that no matter how far he comes, dogs still need consistency. So I always ensure we don't forget where we came from and keep a consistent approach at all times.