Cryptogenic Stroke

I am 69 y.o., meds: Diovan, Simvastantin, Aspirin, Warafin.  On Sept 20 had my second cryptogenic stroke (1st one approx 15 yrs ago) and have  PFO and ASA.  Second mini stroke was in the right posterior frontal parietal junction cortex 4mm in diameter.  Neurologically, I have postural instability (per the neurologist) with the only explanation that this could be related to my left leg weakness from the L4-L5 fusion surgery in 2006.  
Question:  I am concerned about being on Warafin and my instability.  Any literature on this and what about discontinuing my Warafin and increasing my Aspirin to 325 mg instead of the 81mg.  What is the big difference on these two doses as far a effectiveness/prevention.  Why one over the other?

[caregiver222]

There is a lot of literature available on discontinueing Coumadin. I am not entirely against Coumadin, however it is often inappropriately prescribed and continued. And there are many dangers involved in using this medication. The information you request is beyond the scope of this post, however I encourage you to use the MEDLINE database to seek answers to your questions.