Take life as it comes. If you are too sick to take the test, think of it as added time to study for december and get an even higher score than you were hoping for in September. Sorry to hear about that.

You are certainly allowed to reset your watch. The suggestion to have three of them wasn't out of necessity but rather out of convenience. As you are beginning each section resetting the watch is just one more thing to worry about. It should only take 2 seconds realistically but for some people they would rather not have to fiddle with any dials and be able to focus entirely on beginning the next section. The reason that three were suggested is because the LSAT is broken up into two sections of 3 so you could have reset them during the break and not had to worry about it.