Two years ago, before her first level 4 meet, DD got the flu. It was the year of the Swine Flu... not sure if that's what it was or not, but the poor thing was sick... fever, hacking cough, no appetite, etc. She had an 8am meet several hours away and I had booked a hotel under one of those special "cheap but non-refundable" rates. The day before the meet, her fever broke, and she REALLY wanted to go to the meet. We eventually decided we'd go and stay in the hotel (there was a pool, etc.) and see how it went. The next morning she still REALLY wanted to go, so we went. She hadn't eaten a full meal in 5 days and she was still coughing, but we let her go. I know that, if it weren't for the cheapskate part of me rankling at the idea of paying for a hotel room we weren't going to use, we would have kept her home.
We actually were talking about that meet last night. She has a meet next weekend and was saying that she was hoping she'd have a successful meet. I told her that I thought that any meet where she did her best and had fun was a successful meet. She said, "Then they've ALL been successful meets! Well, except for that one when I was sick. I didn't have much fun at that one." In retrospect, I think she probably felt worse than she was letting on. But she HAD been fever-free for 24 hours, so I suspect that she at least was not contageous.
I don't know. It's a hard choice to make. Play it by ear and see how it goes. At least, at level 4, they're not doing any super-dangerous skills where being weak from getting over an illness is likely to result in serious injury. DD landed on her knees during her ROBHS, and I know that was from weakness due to the illness.
Good luck! Here's hoping for miraculous recoveries and no other household members coming down with it!