You're Charles Darwin. And your 5 years surveying the natural sciences around the world on the HMS Beagle have wrecked you.
Mainstream thought no longer seems possible. That every creature in existence had been created instantaneously in one fell swoop. That the fossil remains of extinct species are simply the ones that didn't make it on to Noah's Ark. These assumed truths no longer makes sense with what you're seeing.
And then you notice layers of seashell sediment on a nearby mountain. Realizing that this geology could have only happened over millions of years. Not the 6,000 maximum your peers all assume is possible.
Your no longer know what to believe. And you are all alone.