My 6 month old wont sleep unless I'm near her?

It seems all of a sudden within the last couple of weeks my baby cannot sleep in her own crib. Since I feed anyway I let her sleep in our bed. We have a king so there is plenty of room. However, it's getting to the point where at night she wont go to sleep unless I go to sleep with her. When I put her in our bed, after she falls asleep, she will wake up 5-10 mins later crying unless I crawl into bed with her. I have things to do for the next day and I cannot go to sleep as early as she does. I noticed that she sleeps more soundly on her stomach so I just flipped her over. So far she has been asleep for 20 mins now. She was never a tummy sleeper because I got freaked out about SIDS and she always slept on her back. She can hold her head up and rolls onto her side but never flipped onto her tummy during sleep. Should I be worried putting her to sleep on her belly?