Repeated high fever once in 2 months.

My son 3 years 2 month old. His weight is 14 kg. He got very high grade fever 102-105 farenheit. Also he became so tired so weak that he keeps lying on bed. He eats nothing for 3-4 days. Even he drinks water very little. His eyes becomes red his head becomes warm. We give ibugesic every 4-5 hours and amoxy dry syrup apart of this electral we give him.  because fever again increases in 3-4 hours. It's 2nd day today. And generally fever subsides 3-4 days even after medication. Actually he keeps biting his nails. He is dirty boy. He never listen and eats dirty things . Thts why he fall sick. So we get alarm before 2-3 days about his upcoming fever. His body remains little bit warm for 2-3 days. And cough starts then next 3-4 days very painful. What can I do to stop reoccurance fever . Whatever he gain he looses in these days. Actually his nose always remains dry . He keeps rubbing even there is no cold or anything. But time of fever he cries a lot when he touch or rub nose.