Spiders don't typically bite you hundreds of times. It might just be a coincidence you found the spider, who may have been looking for other insects near you. A spider injects venom under the skin, and this causes serious effects in most people.
This venom will cause tissue necrosis, a black center to the bite and very poor healing rates. Spider bites are not as common as people think.

Collections of bites, could be bed bugs, or fleas, or chiggers (if you have been outside.).
Itching and hives may indicate scabies as well. If you have been to a beach/sand...there are sand fleas and also swimmer's itch. My son has had swimmer's itch a couple of times and was pretty
miserable. Swimmer's itch is a larva of a snail...and is passed into the water by ducks.
http://www.wral.com/golo/blogpost/5478953/

There is currently a huge epidemic of bed bugs in the US.
This is a major problem in hotels and motels now. Even the 5 star ones.
This is a link to what bed bug bites look like:
http://hotels.about.com/od/hotelsecr.../Bedbug-Bites/
These bugs can get in your luggage and come home with you.
Bed bugs hide during the day, and are hard to find.