Why does she keep doing this?

Lauren has been fully potty-trained for over a year now. It was rare that she'd need to get out of bed to go to the bathroom but lately, she has been getting up 4 times in an hour. She stops getting juice one hour before bedtime so we don't think she's drinking too much. We take her to the bathroom right before bed and as soon as we say prayers, give kisses, and close the door, she crawls out of bed and heads to the bathroom again. At first we thought she was doing it just because she could, but now we're not sure. After several nights of her getting up 6 times in an hour, we put a potty chair in her room and told her if she really needed to go, she could use the potty chair. Sure enough the next day there was tee-tee and toilet paper in the potty. Guess who got to it before Daddy? Yep, you must have guessed Caleb. And he poured it over onto the freshly steam-cleaned carpets. Gross! Stephen said no more potty chair. The next night when the games began, we threatened that if nothing "came out" we would take all her friends out of her bed. Well, she got up, nothing came out, and we took her friends. She didn't get up again that night. We wondered if there could truly be a problem so last week Stephen took her to the doctor. They ran tests and all the tests came back clear. The doctor did say that it could be a "tickle" where she thinks she needs to go. That made sense, there was a time that she went to the bathroom, we loaded up the van, and as soon as we pulled out of the driveway she said she had to go potty. Last night we were at our wits' end. It was already after 10 which meant Stephen would get less than 5 hours of sleep and after all the work he's done (see post below), he is physically and mentally exhausted. I was nursing Abby and Lauren got up even after Stephen took all her friends AND threatened to take her Piggy the next time. Piggy is her BEST friend. He has been with her her whole life. She has never had to sleep without Piggy. We didn't want to do it, but she got up again. And there was no tee-tee. So Stephen took Piggy. I've never heard her scream and cry and yell like that before. We were lucky Caleb had not woken up in the adjacent room. Stephen looked at me and told me that is like taking away someone's baby. We felt horrible and tried to come up with an alternative. Pull-ups? Stephen went in to trade Piggy for Pull-ups and Lauren didn't want to do that. He tried to talk to her and she said she wanted to talk to me, that's funny, does she think that her daddy just doesn't understand? So she got up on the bed with me and talked it out like a 15 year old, "Mommy, I don't want Pull-ups, I'm not a baby." So I told Stephen that I didn't like the psychology involved and wanted to try something else. After a long talk, I asked Stephen if we should try the potty chair just one more time. At least she would not be bothering us. So we agreed and Lauren did not leave her room again. As a matter of fact, before Stephen fell asleep, we heard the lid of the potty chair go up.....and this morning there was potty with a neatly folded -into a square- piece of toilet paper in the bottom (she's OCD too...read earlier post). So, anyone else experience this sort of thing?