I had a emergency removal of large menigioma. After several gran mal seizures they found this tumor - larger than 5 inched diameter. this was removed 3 weeks ago and I have been home for 2 weeks. The last several days I have been getting lightheaded when sitting down. I almost feel that I am losing conscience. I am taking Oxycodone 5/385 3 times a day. morning/noon/eve What is going on - I am concerned