Twitching/spasm feeling?

I'm 21 weeks and 3 days today and all day long I have had this non stop twitching spasm feeling where the baby's feet usually are on my left side of my belly. Is this her kicking constantly?? Or is it just something weird that's happening? I have felt her little flutter kicks like normal near my pelvic area today also but it hasn't been constant in that area just on the left side of my belly. Has anyone else had this happen to them?