My Son-in-law Works In Construction,its His Company,for The Third Time

My son-in-law works in construction,its his company,for the third time in two months he's suffering from a high fever (sweats through four or five pairs of clothes a night) he has a severe headache that doesn't allow him to sleep but for a few minutes. He can't poop,can't drink more than a few sips at a time or he becomes sick. He went to the er they gave him intervenous fluids and sent him home.