i'm sorry you're going through this and hope you have sought medical treatment. unfortunately it's impossible to diagnose a condition like this without a physical exam. many conditions can cause the symptoms you describe. a medical professional needs to see this and possibly run some additional tests in order to figure out what's going on. meanwhile be extremely careful not to touch surfaces or other people while the rash on your hands is active. wear light gloves if possible to keep from spreading whatever this may be to others. i hope you get a diagnosis and feel better soon!
itchy palms and fingers bilaterally_turned to multiple tender blisters over past 12 hr_now tender blisters back of neck