Sounds like me with DD2 but it hit at 5 and half months. Perfect sleeper till then and now she wakes up about 4-5 times a night. I am riding it out too. We have ended up doing a lot of co sleeping which helps a bit. I did find that she liked some sort of noise when she was sleeping so majority of the time during her day sleeps I have the radio playing or a musical toy. I guess it is not to bad, it always feels worse at 11pm, 2am, 4am and 6:30am when I am up again and DH is happily snoring next to me.
DD1 is the best sleeper, we never had any issues with her.