What Causes Increased Sensitivity Of Smell And Abnormal Behavior?

my wife has started to be very sensative to items like, sentented candels, fabric softener, shower cleaner, etc and has began removing them from our home. she is 64 years old and I'm concerned that it may be some sort of mental illness. She was present when her mother died and has acted stange since then. She ask her primary md. about ptsd but passed the test. Please advise.