Help! I need ideas to help baby sleep?

My 3.5 month old used to take regular 2 hour naps and then sleep at night from 9p-5a and take the pacifier at about 3a until 5a when she would eat. Now she is only taking 30-45 min nap and waking up 4-5 times a night. She still goes to bed at 8:30-9:00 but wakes 4-5 times between 12A and 5A. She is not screaming like she is hungry until the 4-5am wake time, but she cries and tosses and turns and will not go back to sleep without her pacifier, but only sleeps like 30min-1 hour before rising again. She seems to sleep better on her stomach during the daytime when I can watch her, but I am afraid to do this at night as she is not turning over yet, but I think she would sleep so much better. Any ideas?