Mysterious Pains are DRIVING ME CRAZY

I am at my wits end with my girl and her mysterious leg/feet pain. Tomorrow will make it the fourth week of excruciatingly long bedtime rituals that include tired tears, screams, facial contortions, and frantic feet kicking under and over the sheets. She acts as if she is in so much pain that I have to imagine there is some kind of tumor growing on the part of her spinal cord where the nerves that radiate into her feet reside. What other explanation is there and what else can I do? I increased her Motrin dosage and it does nothing. I tickle, massage, sing, say soothing words and then I threaten, beg, and bargain with new bicycles, trips to Disney Land, etc. I even said a prayer with her tonight and when it was finished she said, "it didn't work. They still hurt." Whilst I was tickling I remembered a scene in Gone With the Wind where the black slaves have to fan the Southern belles while they take their afternoon naps before the Wilkes' BBQ. I feel like the slave with the tickling fingers only I can't get my charge to sleep. The last couple of nights I've just been letting her cry herself to sleep because it is the only way to get results but that doesn't seem right either if she is really in pain. Bedtime has been taking up to three hours. And then she is so miserable and tired all day long. Arrrggg!