I do feel ur pain! I’ve gone through with something similar with google…have a domain which was all over the place in the google serps – disappearing and re-appearing, getting traffic for keywords when i couldnt find myself in the serps. went on for a couple of years and then this year it returned back to normally. It went from 8k uniques a day to 2k, and after all that 4-5k a day.
I didn’t find google particularly helpful in trying to fix whatever the problem was.
But if u want to chat on Skype and see if we can explore possible solutions, am happy to help. Pm me!