I've recently moved into a new house and i was told that there had been about a month with no occupants before me. I brought my old mattress that was given to me by someone into the bedroom until one nite, i woke up from a firery stinging sensation on the joint of my forefinger. I thought it was a flea bite from the old mattress so i brought the mattress out of the room, leaving it standing by the doorway and bought a new bed. As I am writing this, I am still bothered by these stinging sensations all over my body and I see welts that swell up only to a size of a ball-point pen (but still itches) and I can't figure out what's biting me. I have ruled out fleas and bedbugs as I've read that they are somewhat visible to the naked eye (and I can't see them). Am I imagining these bites or are they really there? What are they and how can I be relieved of this stress that sends me over the edge every nite I am trying to get some good nite's rest?

Thank you so much in advance