Is it normal for fetal movement to be more mellow after days of extreme fetal movement? I'm 27 week and 4 days.

Yes and no. Your fetus's activity pattern will vary hour to hour and day to day - much like anyone's activity. Of course, the absence of fetal movement is very worrisome. A decrease in usual fetal activity day after day can indicate that your baby is having some significant problems. This should be evaluated by your caregiver immediately. In general, if your baby moves more than ten times/hr it is doing well.