For the most part, this is a strongly written piece. I say for the most part, because you consistently do one thing that always makes my hair curl in frustration. Check out this sampling from the text:

Dana studied the man still asleep beside her. His back was turned, but she could tell he was well built. Probably why I ended up in bed with him. She thought.

His back was hairy and covered with several large red pimples. He snorted loudly and rolled over, covering his eyes with a meaty arm. He had more of the angry red blemishes across his shoulder and chest.

Oh my god, how drunk was I to miss that? She thought.

In the first place, all those she thoughts should be part of the same sentence, separated by a comma. In the second place, they shouldn't be there at all. Compare this version of the same passage:

Dana studied the man still asleep beside her. His back was turned, but she could tell he was well built. Probably why she ended up in bed with him.

His back was hairy and covered with several large red pimples. He snorted loudly and rolled over, covering his eyes with a meaty arm. He had more of the angry red blemishes across his shoulder and chest.

Oh my god, how drunk had she been to miss that?

Here's the thing: you're telling this from a third person restricted point of view, which means that anything that is present in the text will be something that is first filtered through Dana's perceptions. In other words if it's a thought, we already know that Dana is thinking it. Incorporating all those quoted internal statements is needless baggage, when they can effortlessly be merged into the narrative stream without breaking the rhythm or the perspective. You do it a lot and it becomes the kind of repetition that you never want to force on your reader.

Other than that, you write fairly well, at least as far as the nuts and bolts of your prose is concerned. I'm far less confident about what it is you are choosing to write. Or, more to the point, how you are choosing to present it.

You have a standard alien visitation set up here. I say standard because most set ups are. The truth is in the telling and I simply can't buy Dana's reaction to the utterly bizarre events overtaking her life. I'm not too concerned with the fact that you do nothing to explain the alien presence; in the real world, such a visitation would likely come without explanatory notes or background information. But in the real world, we would expect Dana to move through a series of transition moments as she first denies the evidence of her eyes, then rejects it, then tries to negotiate with it (I must be tired) until, at last, she, and the reader, are brought to the confrontation with the impossible that is, nonetheless, clearly present. We would expect some measure of resistance on Dana's part, before finding herself absorbed into her new, alien environment.

We find none of that. From the first encounter with the blue spider, Dana greets each new horror with the same reaction that might accompany her thinking "Oh gosh, I forgot to pay the utility bill." Truly horrific scenes, ably described, where her body starts to come apart, are robbed of their emotional impact simply because they seem to have no impact on Dana.

One hears much about the willful suspension of disbelief in the process of appraising a work of fiction. Never is the issue more crucial than with a story like this one. You are asking your reader to follow you down the rabbit hole, which, I might point out, they are more than ready to do. But the the first time you evoke a response on the order of, "Aw, shucks, she wouldn't act like that," you've lost them, and you won't get them back.

Moving on to some Plot—101 issues, I note that you never really move out of the realm of situation here. Dana finds herself in a strange situation, and, while it gets stranger and ever more strange, it's just a situation. Not a story.

For a story to grow out of this situation, one needs to ask oneself, "So what?" Given that these are the conditions in the specialized universe in which Dana finds herself, what happens now? What complications appear that she must address? What decisions is she forced to make, what actions is she required to take? What are the implications of those decisions and actions? What effort is required of her as she attempts to resolve her difficulties. In other words, the transition between the beginning and the end, which is where stories take place. There's really no transition here for Dana. She has disintegrated, true, but she's remained a passive observer while all this strange stuff is being done to her. The reader has no one to cheer for. No one to identify with. Dana makes no effort of any kind and so there is never an opinion about her that is allowed to form in the reader's mind. At the end, all they'll say is, "Hmmm. Interesting."

You have the potential to wring a much stronger reaction from your readers, but in order to do so, you'll have to make Dana a compelling character, one who struggles against the odds. Whether she succeeds or fails is not the point. What will keep the reader reading is her ongoing saga.