Weird things happening with my muscles...!

Seems like over the last month I've upped my intensity a tiny bit with my running.  Funny thing is, when I'm at rest...sitting at the computer, driving, or just walking about, I frequently get these weird muscle sensations in my calves and hamstrings.  It feels like a "ball" of tightness that kind of just drifts about up and down my calf muscles and hamstrings.   It literally feels kinda like it moves about a little bit.  Its annoying.  If I massage the area, it will loosen up but only return later.  The medical term is probably some sort of spasm I'm thinking.

 Another thing is I stretch out a good bit before and after running but it seems like my muscles keep getting tighter.  

 If anyone might have any advice I would be very appreciative.   Thanks!