yea its hard to find info on this... this might help in my location when someone has what you posted its called lack of affect. its a symptom of many mental and physical health problems and even things like lack of sleep, poor diet and medications can cause it.

my suggestion is contact your or a treatment provider in your location. they will be able to tell you what this is with in you and what types of diet, meds and other things can help you with this problem.