I found my son had about 3 weeks of unsettled nights right about when he hit 6 months. He went from feeding once per night to 3 times a night and, for the first time ever (including when he was a newborn) had a couple of nights where he was up for hours.

Nothing I tried really worked (sorry ), but we did get through it. He also popped out 2 teeth just after, so I thought that might have had something to do with it. On the plus side, after another week of being back to 1 feed per night, he is now sleeping through