What Causes Scratches On Thigh After Lindane Treatment For Lice Infestation?

I am recovering from a body lice infestation. I read where they can also cause scratch marks. I have done two lindane treatments, about two weeks apart. There was some conflict with my regular md and derm. My regular md stated I was lice free over a week ago. I noticed a couple of bites or bumps and saw the nurse practioner a couple of days at my derms office and she too thought I was out of the woods. She did recommend I do the second Lindane treatment. I did this two nights ago but noticed tonight I have a scratch on my thigh. I did not cause this. Could this be from the Lindane or my body recovering?