My dog.

Two or three weeks after he died (evil <swear word> of a neighbor poisoned him), my right hip went numb. I had no idea what caused that until later that year when I got optic neuritis and they said "you might have MS".

That dog always knew when I was sick and not feeling good, and would come up to my bed and stick his head over the side (he was a REALLY big dog. His name was TinyMonsters) and just check on me. I really miss that sometimes when I don't feel good. I always knew when he didn't feel good either.

I pretty much went from a person who was healthy and was walking my dog around the block all the time to being the person I am now that feels like I'm drowning in MS-ish goo all around me all the time.