Telling Ennis about some weird hallucination or fever dream you had about her brother is about the stupidest thing you could do right about now. Sure, the whole thing felt real at the time, but you know better than to buy into it. You need answers, that much is true, but talking to Ennis isn't going to help you find them. She's not a neurologist or a psychologist. She can't tell you why you're seeing things that can't possibly be real.
Once you find answers, it will be clear there is nothing worth being scared about.
The trilobite is still in your hand.