Eye Fluttering with positional changes

I am a new mommy and my 4 month old daughter has been having episodes of eye fluttering with positional changes, especially when being put down on her back off and on for about 2 months now.  When the episodes occur, she flings her arms out to the side and her eyelids flutter rapidly. At times she will also almost seem like she is smiling while the episode happens. The episodes last anywhere from 5 - 20 seconds and at first did not seem to bother her, but now when they occur she turns bright red, as if she is holding her breath, and then belts out a cry. I also feel like afterwards she has a sort of blank stare, almost as if she is confused. I have taken her to the ER and have taken her to her Ped. I showed them a video of her having an episode and both the ER md's and her pediatrician were not concerned. They called it a startle reflex and stated most babies do this. I am not convinced that this is normal, as it seems to bother her. Coming across your post has given me hope that we can get answers as to why she is having these episodes. My baby girl is in the below 5% of normal baby weight. She is strictly breastfed and her Ped is not concerned about her weight. She is reaching her milestones much earlier than the average baby and besides these episodes is happy and healthy. Has anyone had similar experiences and can give me some insight as to why this is occurring?