Doris the buckeye hen . . . lonely, molting or bugs?

My precious 3 month old (+/-) Buckeye hen, Doris, is alone in her run for the moment, her rare breed buddies were sold a week or two ago. I have noticed an increase in the number of feathers in her pen. She is still active, eating and drinking. I make sure to give her more one on one attention and treats since she is the only-bird (until this weekend). She ocassionally scratches her head and sometimes other parts of the body. but not excessively. She looks a tad ruffled but not patchy or sickly. Can a pullet this age molt?

I am relatively new to birds. how do I check for mites, fleas etc? Should I trea her and the run with D.E. to be safe? I hate bugs and the idea that she may be infested makes me sick to my stomach. I don't know what to do! She is still on grower, but am slowly switching her to to finisher. She gets seeds, fresh veggies/fruit, crushed granite and meal worms on a daily basis and has 5 gallons of clean water to herself. Am I a bad mother?! Help would be appreciated, I want this resolved before my 3 White orp pullets come Saturday! Thanks in advance guys!