Baby shaking in womb?

So I’m 27 weeks and for the past two weeks every night when I lay down it literally feels like the baby is having a seizure in my stomach. It feels like she’s kicking and hitting very fast for a good 10 seconds and keeps doing that for a good 30 min. Like she has uncontrollable twitches. My OB brushed it off as we don’t know what she’s doing in there, but I’m really concerned. Anyone having or had the same experience??