Every so many days/weeks in notice a vein/artery in my leg thats seems to be spasming, sometimes in my arm, too. I guess it could be a muscle fascia (sp?) but it seems to pulse with a kind of heart beat regularity. What is that? It’s kinda gross. 
It happens to me too. It feels like there are air bubbles or something like that in my vein. I’ve had it in my arms, though, too.