Bed bugs or horse hay chiggers ?

My wife went to a Fl. resort last month and within a week of returning complains of bites/welts mostly on her torso, noticing them in the mornings. We have stripped the bedroom of rugs, cleaned her clothes in dressers, sprayed bedbug/flea spray throughout the drawers, around the bed , on the mattress, bombed the bedroom and living room twice, and spread diatomaceous earth throughout the bedroom on/under the bed and frame where it still sits in piles of powder a week later. We put the mattress in a microfiber anti-bedbug cover. I have yet to be bitten, sleeping in the same bed. I have O pos. and she has A neg. blood types. In tearing down and treating the bedroom twice now, I have yet to see any evidence of bugs/fleas or droppings. We are in a humid , buggy part of N. Ga. and she "lives" in the barn caring for two equine, handling bales of local hay several times a day. I am convinced the problem is NOT in the bedroom but in the barn. Her co-worker who stayed in the same hotel room has not had any problems, but she kept her suitcase on a hard floor while there and my wife did not. Any ideas before she forces me to steam clean the entire house ?