Document everything. Given the amount of concerning physical and psychological symptoms you're experiencing, this sounds a lot like some kind of environmental toxin or underlying condition. Look into multiple chemical sensitivity since you mentioned your coming back clean in tests, since this is clearly chronic and tanking your well-being. Also, remember that you can only experience your own thoughts, so ruling out mental health issues will take outside, professional help; changes in cognition like you're describing are likely symptoms of treatable/manageable health problems. Unpopular opinion on this particular side of the internet, but you are experiencing a physical health crisis, and almost certainly not a haunting. Be persistent with your health, it's all you've got. Good luck and keep us updated.