I need help with diagnosing my wife's bedroom allergies! ?

We live down in Austin where cedar allergies are off the charts. We have no pets (she is allergic to cats). My wife really seems to be struggling with these allergies but strangely they only affect her in our master bedroom, beginning this last month. Before that she was fine. As soon as she goes to bed her nose becomes completely congested making it nearly impossible to sleep (for both of us). Once up and around all symptoms seem to subside. This leaves me to believe it is not a cedar allergy so I am baffled. Tonight we will try sleeping in the guest room and I'm thinking I will take the comforter to the cleaners and replace all the pillow cases. Does anyone have any feedback or suggestions that might shed light on what I am not thinking of? Sleepless in Austin......