We had the same reaction with apples. When I finally got my DS taking decent naps, he did a fabulous morning nap for about 10 days in a row. Then all of a sudden, one day it was back to 30 minutes. After 3 days of this, I realised that on those three mornings, he'd had apples (for the first time) for breakfast. The next day, no apples and he was back to a long nap!
I always had tummy aches from apples - right through until very recently. I mentioned it to my paed last time I was there for DS's milk allergy to be checked-up on, and he told me that often it is the sugars and pectins in apples that causes a reaction, and it can be anything from a rash around the mouth to tummy aches. He told me to stay off of them for a while and then try them again in a couple of weeks to see how it went. I waited a month, tried apples again and had the same reaction. Waited another 2 weeks and tried again, and that time DS was fine. And, ever since then, he's been an apple monster, can't get enough of them!
I can't see it being any different with pears than apples. I used to think DS just didn't LIKE pears, but then started to wonder if that was causing the same problem. When I first introduced pears he wasn't sleeping at all anyway so I wouldn't have noticed any difference, but it's possible they were causing him some tummy problems as well.
I would cut out the apples and pears for a while, and see how she is. Wait a couple of weeks and try again, choosing just one, for a couple of days and see what happens. If you get the same result, you know it's something in the fruit.
