First thing I notice, the font you chose is tiny. It makes it hard to read and can lead to fewer people wanting to read and review. Pump up the font size to at least 3.5 or even 4.

You only chose one genre. You have three to use. You have better chances at having your stories read if you include as many genres as possibly fit your item. You could have added Dark, Death, Drama, Occult, Mythology, Folklore, Paranormal, Supernatural, or Tragedy.

The story was entertaining to read. I liked the backstory of the two brothers and how they have a tradition of camping since they were little. You could add a little more of an explanation why the brothers choose different spots for camping while grandpa always took them to next to the barn. That was an opportunity to explain their behavior.
The ending of the story is very dreamlike. As if you had a nightmare while a train was whistling in the distance. It would be neat to know where that monster comes from, or if it is the first time there. It's mere existence is obviously scary, but all areas have a local lore about some monster or the other. If this one is a newcomer, then even that bit of information would make the story more rich.

A couple of suggestions for editing:

"Sounds like a plan" I said Missing punctuation. This should be: "Sounds like a plan," I said. There are more instances like it. A slow read-over to fix all of those missing end of sentence punctuations and missing commas around speech tags would be great.

my drunken haze. Lay there for a couple of minutes There is a word missing. It should be I lay.

I hope my comments helped you to see the story through the eyes of another.

If you go to the left side bar and click on My Account and then go to My Activity and choose My Achievements, you will find a couple of neat surprises in your email inbox.