Hello? The baby's temperature rises to 37.2-37.3 in the evening when …

Hello? The baby's temperature rises to 37.2-37.3 in the evening when we go to bed. I give him breast milk, he sweats slightly and it normalizes immediately. The private pediatrician in the check-up appointment said to have a blood test for CMV. Positive, of course + during my pregnancy I had them. Here but not categorical norms. Did you have something like this? Because of what could it be?