Good morning Kaitie :)
I always get in trouble with my Veterinarian for doing research :) I'll come up with various ideas for what my dog could possible have and he just smiles and says, "You've been on the internet again."
Carbon dioxide imbalance is just one possibility. It turned out it was, for me, the reason I had night panic. There's different physical reasons that could contribute. But, regardless, even if you don't know specifically what it is, you can still overcome it by positive truths, this is just temporary, it will subside on it's own, I can handle it, etc.
Sometimes I look up what my dreams mean, online. Spiders could symbolize something other than just being about spiders. I've found 3 things about dreams, sometimes they are just that, dreams and they make no sense. Other times, I'm working out some problem or issue or it lets me be aware of what my concerns are. And, then again with symbol dream interpretation, I sometimes find it's either spot on or it's complete hooey. I go to dreammoods.com, even if it's hooey, I can still get a laugh out of it and it makes the dream less scary. And, if it turns out to be spot on, I feel peace knowing why I dreamed it and I can move on.
I'm not sure if your afraid of spiders or not and that's why you dream about them, but my daughter has a spider phobia, because she got bit on the leg when she was a child. However, this summer she bought a rather large Pink Toed Tarantula to get over her fear (I'm not telling other people to do it, I'm just mentioning what my daughter is doing :) She still has fear, handling her, but she's slowly overcoming it and is determined to be comfortable around her. I'm not afraid of spiders, but they wouldn't be my first choice of cuddly pet, although they are pretty cute (to me) and fuzzy :) I guess it's all in your perspective.
Shari