Advice?

My lo is 2.5 years old. Friday after his nap he woke up with a fever of 102.5. Then all he wanted to do was sleep. He kept crying and said his head was hurting so I gave Tylenol. Fever went away. Saturday, same situation. No fever all day until nap time. When he got up Saturday it was 102.6. Within an hour it climbed to 103.3. We decided to take him to urgent care because to me he was showing signs of the flu. They take his temp there and it was 104.5. They did a flu test and it came back positive for type a. They gave Tylenol and made us wait to see if it came down, it did. They sent us home and told us to keep an eye on his fever. Last night his fever got up to 103 again but he was sleeping so I didn’t bother him until he was uncomfortable. Since it was too early to give Tylenol I gave him a bath at 2 in the morning and it brought his fever down some. At night is when his fever is bad, which I understand cause body temps rise at night but tonight before bed I took his temp and it was 100.3 and about 30 minutes after I laid him down I went to check on him and he was clammy and sweaty so I checked it again and it dropped to 97.1. I’m just wondering if a drop that big is something I need to be concerned about? Is there any complications I need to watch for with him only being 2? Sorry it’s so long but just wanted to get advice on what I should look for.