Nighttime wakings! Help please?

My 6.5 month great sleeper has been waking every 1-2 hours during the night. She's on a pretty good bedtime routine and while the weekend was a bit off on timing, her routine was consistently followed. She starts waking around 10:45pm and then after 1:30am, every hour she would wake crying hysterically. Took her to peds and she said she's fine. No ear infection. She doesn't have teeth yet and drinks 4-5 oz 6 times a day and is offered solids 3 meals a day. Any suggestions on why this could happening? And what I can do?. Please and thank you!