Low grade fever not going away

We are going on a week of my baby being sick. He had a 103 temperature last Thursday night, it came down with motrin and I took him to pediatrician the next morning. She said his ears looked good and that it was probably something viral. I kept him on motrin and he stayed around 101. By Sunday he was down to 98 and I thought it was over. Now every day this week, he wakes up with no temp (around 98) but after playing and being up for a couple hours it creeps up to 100 (it hasn’t gotten higher than that all week). He’s still congested and I can tell he’s not 100% but he’s also not miserable. And he doesn’t have any other new symptoms. I plan on taking him back to doctor in the morning. But has anyone else dealt with this? Is this just a virus that won’t away?