Sophie Is Missing

Sophie is one of my feral cats, who has never lost her fear of humans.  Unlike the kittens who were born out here, and grew up around Dave and me, Sophie was already an adult cat with all her feral tendancies firmly ingrained.  In spite of this wild streak, she saw us as reliable sourse of food, and stayed.  Each morning, she comes to the food trays, eats, then goes to my neighbor's yard to nap or hide.  I grew to love her and count on her presence even though she's never been friendly.  During the time we were doing our TNR, she became wise to the trap, and was actually the last of my ferals to be spayed.  I still don't know what made her decide to walk into the trap that day, but I'm glad she did.  That day marked the end of her kitten bearing days, and the beginning of her carefree days of running, playing, and napping in the sun.
I don't remember if it was August or September, but I began to notice her developing a skin problem.  It broke my heart, because I knew she needed help, but would never allow me to help her.  I began to try harder each day to reach out to her and win her trust.  I wanted to take her to see the vet.  My efforts had just the opposite effect.  She became so freaked out by my attentions, that she wouldn't come to the food trays until I'd gone back in the house.  For months, I watched her skin conditions spread, and her misery grow worse, despite all my efforts to reach her.  About a week ago, she was eating, and while she wasn't paying attention, I reached down to pet her.  She didn't run away.  Great! For the past week, I've been petting her each time she'll let me, thinking maybe she'll finally trust me enough to let me help her.  Two days ago, she was in such a miserable condition, that she actually came up to me.  Reluctantly, but still she came up to me. Today, I called our vet, and explained what she looked like, and how she's been behaving.  He knows I work with ferals, and tries to help me when he can.  He recommended a heavy dose of Advantage Multi, which kills all kinds of skin mites as well as fleas.  I have the medicine, and am ready to attempt to dose her as soon as I see her again.  The bad news is that she's been missing since yesterday around noon.  The last time I saw her, she was wondering over to the neighbor's yard, her misery causing her to let out a wimper now and then. 
Please, God, let her come back.  Please don't let that be my last memory of her.