Which is it?

Are my headaches caused by exercise or blood thickness?  This is a great example of isolating a symptom and determining it's effect.  Except I have compounding factors.  My INR is 3 which is as thin as the doctors want my blood to be and I have quit exercising.  Is it both or just one?  I would like to continue walking and being  a little active but not at the risk of causing harm to myself.
Therefore today I went on a walk in Golden along Clear Creek.  I highly recommend it, nice path, restaurants along the way, and the creek running rapidly towards the Coors plant.  I thoroughly enjoyed it and am hoping there will be no headache to follow tonite.