Hello! My son recently got a roseola. Then after a week, he started no…

Hello! My son recently got a roseola. Then after a week, he started noticing a yellow tinge on his tongue. We're giving him mashed avocado every day. Cookies, porridge, apple. And twice a day, formula. And we eat what he eats. We see the doctor only on Tuesday. The baby is not bothered by anything. He plays, eats, sleeps. What could it be?