also, Glass Owl, if I were you I would wear it as a pendant - the larger the better, and wear it near the heart, the center of all circulation...make the chain or strap or ribbon just long enough so the pendant hangs exactly at heart level, with the top being up near the top of the heart....you could also wear earrings too, since strokes have to do with the head...
The others here have all given you great suggestions for beneficial stones to use, and there are also these (with some repeats from the others, lol!)
stones for the brain are aqua aura, amazonite, opal aura, lapis, rutilated quartz, turquoise...
for circulation of blood, carnelian, garnet, ruby, and both tree and moss agates.
ETA - Glass Owl, I just read that the Almandine garnet is the correct garnet for the blood clot issue...fairly common, so should not be hard to find, nor too expensive -