I use to have this problem when I was younger and never really thought much of it, but recently it's started happening again and it's starting to concern me. It's really had to explain in words, but basically my body will kind of have the quick pulse every few minutes. It's similar to the jerks you feel when you're starting to fall asleep, except it's all internally (i.e. my body itself doesn't actually jump, my "insides" do...if that makes any sense at all). I'm starting to think it might be something neurological because I was talking with someone who seemed to have a similar problem and they describe it as "electrical-like pulses". I've been dealing with really back sinunitis lately, which has made me have really dizzy spells, but I've had this problem in the past so I'm not sure if it's related.