Girls, what can I do if my child is nauseous from everything? But not …

Girls, what can I do if my child is nauseous from everything? But not throwing up, just a gag reflex and therefore doesn't want to eat anything. Some kind of stomach upset. Recently, she was coughing for three days, on the fourth day her temperature rose by one degree, we brought it down, then it went up to 37.5, and immediately started sweating and letting go. Now she drinks water, sucks but is nauseous from everything. To say that yesterday she went three times, a little watery, but not very much ?‍♀️