I am experiencing same symptoms and since i've been reading different forums on the internet I do believe that these are all related to perimenopause since so many others are having the same symptoms.
Sometimes it feels like my heart flutters or quivers, sometimes I feel a thump, or sometimes it just makes me jerk all of a sudden. But they all last just a matter of a second or two. It is always scary when it happens and you wonder what's going on. I have been getting more use to it and it doesn't freak me out like it did at first but it still makes me a little anxious.
My periods have gotten heavier too and the Dr. Told me I was low in iron which can be because of the heavier periods.
Hope this helps some. I know it helped me just knowing that others were having the same symptoms.