What Causes Numbness In Leg, Tremors And Fever?

hi, i have had 3 incidents that starts with numbness of my leg all the way up to my thigh, then shivering starts heavily, lasts for 30 min, and then i start getting fever (38.5 was the max reading). i have been hospitalized yet no one knows the reason behind that. I had thyroid cancer 3 years ago and currently on eltroxine 150