My Wife Has Been Placed On Xarelto About A Week

My wife has been placed on Xarelto about a week ago - she had a PFO about six months ago. During the past week she has been very tired and had some headaches and her balance has been affected numerous times during the day. Her energy level is low. I have concerns about her on this drug - are my concerns valid? She was on Plavix previously and had a negative reaction. Should we be asking for certain tests on her to be conducted to determined side affects of Xarelto?