I woke up at 5:50am with a burning itch on my foot, and found three bites on it. They looked like mosquito bites, but I don't think they are because we don't really have too many mosquitoes here and keep all of our doors and windows closed. When I woke up, my foot was sticking out of my blankets so it was exposed. I don't know if they're spider bites or bed bug bites.
I just inspected by mattress and box spring, and found two shell casings of something, some other foreign objects that may or may not be related, and what looks like a dropping stain. Are these bed bugs, carpet beetles, or other?
Potential droppings:
http://imgur.com/a/4GDXG
Shell casings on the left and foreign objects on the right:
http://imgur.com/a/dV2AN
Thank you!