I doubt 3 weeks of ostarine is the culprit, could be a great number of any other factors too. You also didn't provided a baseline for comparison or include any other life style factors that might have made it higher. Mine gets a little high just from eating 5000mg of salt in a day or having to much caffeine. (Going by the crappy BP tester at my CVS). I would say test it again on one of those testers at the CVS or grocery store to see how it fluctuates, and look up the factors that might increase it temporarily and compare your BP numbers to events in your life that might have jacked it up. Also your doctor will probably consult with you and help you trouble shoot it anyways unless you did PrivateMD or something.