Hi! In dream interpretations, spiders are often a sign of stress. There's a few different ways I've seen them interpretated. They could mean a lot of little things are "bugging" you right now, getting on your nerves. Or you could feel like you are being imposed upon/being taken for granted (that would make sense with them being on your body).
I have really intense car crash nightmares when I'm super-stressed and feeling like I'm losing control. I can happily say those aren't premonitions. Usually what helps for me is to write down during the day what is bothering me, looking over it, maybe even trying to find solutions. Also relaxation methods help too sometimes