Hello. My 27 year old son who is tall with a very fine body build, has been over the last few years having episodes where he gets tunnel vision, cold sweats, numbness in his arms and hands, slight headaches. We realized that these attacks came on after eating foods that contain MSG. He also had a fairly prolonged episode after going into the ocean, and before his band had a performance. 12 months ago he had a very stressful close encounter with death through no fault of his, and since has had a few episodes of the above. Could this be a low blood pressure, and, or, a stress related thing.