3 week old baby with fever

I’m currently at the hospital with my baby because he has a fever of 100.7 , I’ve been here since last night they runned blood test, they got liquid out of his spine too !:/ because they can’t seem to find what’s making him have a fever , his fever went down a bit to 99.6 in the morning and now it’s at 100.8 again :( they’ve been giving him Tylenol and he’s on an IV and they’re still running test like takin booger’s from his nose and pee. I’m a first time mom and I’m really scared has anyone else gone thru this ?