I Suffer From Sudden Severe Nausea, Heart Rate Speeds Up,

I suffer from sudden severe nausea, heart rate speeds up, temperature rises quite a bit, I feel really warm, my whole body shakes for a few minutes then stops and starts again, I struggle to control the shaking. I am not on any medication I don't drink or smoke or do drugs, it's not caused by anything I eat as it happens at all different times day/night and I don't drink anything with caffeine. Iam healthy apart from this, when it starts I have to stop whatever I'm doing a sit/lie till it passes, sometimes it last 5mins and other times it can last hours. My medical record is very small as I have always been healthy, not had anything prescribed since I was a child. Any idea what is wrong with me?