My 2.5yo DS has been reliably STTN for about 6 months. Recently he has started waking multiple times per night, lots of squirming and crying. Picking him up / cuddling doesn't seem to help, which makes me think he's in pain. He settles himself to sleep at the start of the night and still has an hours nap. I can't think of any changes that could have caused such a sudden change - does anyone have any ideas?