Gas problem

The last few days, my nearly 5 month old DD seems to have been farting a
lot, especiaally when she wakes during the night. She squirms as though her
tummy is uncomfortable (though this is just my interpretation) then lets one
off.

Is it most likely something I've eaten? I can't think of anything I've eaten
recently that might have caused it. Or could it be some stomach bug she's
got? Or is it nothing to worry about?

Thanks,
Liz