I don't understand...

I woke up this morning with a sore throat, swollen gland, and ear-ache, all on the left side of my head and neck. The right side of my head and neck feels just fine, isn't that weird? How does a virus or germ or whatever it is enter my body and decide to attach itself to a particular place? Why did it pick me at all? I never purposely did anything to this thing to cause it to want to attack me (at least not that I know of). I was fine when I went to sleep last night. Did it sneak into my bedroom while I was sleeping? Or did someone secretly pass it on to me yesterday at work? I have been being healthy lately, working out, drinking lots of water, getting a good nights sleep, and this is my reward? It doesn't make any sense to me. There is so much about the universe that I don't understand. :-(