Oh my, I am so sorry--your story sounds familiar, almost exactly what happened with Eloise. I haven't been on here in 3 weeks because of following up with her, it just threw us all off the first little while.
We went to our local children's hospital urgent care, so when they did the testing, they mentioned a spinal tap--the doc took one look at my face and said, let's just run the RSV test first and see how it comes back!!! I think she knew she'd have a major fight on her hands. I knew that test was for menengitis, but Eloise didn't have her vitamin K yet so I was really leary of doing anything that invasive. We ended up doing the vitamin K upon admission so the deep suctioning for the RSV wouldn't hurt her in terms of bleeding/bruising. But still!
Just be prepared for it to get worse for 3-5 days before it gets better. We went in the minute she ran a fever, like you did, and spent 48 hours at the hospital but did not need O2 or IV fluids, and only needed deep suctioning a couple of times. They sent us home, and she did well for 48 hours, and then worsened. It was scary and discouraging to go back. When we went back in, she needed all the treatments, and we were there from Thursday to Sunday. Then we've been home since, but I've had 1 or 2 sleepless nights where I've been worried about her.
Then, she's still congested (our Dr. said that could be another month or two) and it makes her gag, so we have a lot of spit-ups, which bugs me. I try not to worry as long as she seems satisfied, has poops, and is gaining, but I'll be honest, I worry about her intake since she vomits so much. ARGH. Just hang in there, it does get better, just know it will take time and this will be a rough winter recovering from it.
It's hard to not take my toddler to the park on days it gets above freezing here, but I just know I can't have her out in the weather until spring comes. . .just a few more weeks!