Is s/he on solids yet? How about at night?
DD2 will be 6m on the 27th and last couple nights she has been waking up every 45-60m. Just before that things were getting better again and she was even going 4-5 hrs for her first stretch. But then at 6m there is a growth spurt so she can be hitting that early.
Tonight she has already woken up 4x since 7:30!!