My father is a tobacco addict. His gums became dilute along with ulcers in his mouth two days ago. He had fever and having constipation. He said that he stops chewing tobacco few days ago and then these problems occurs because of change. Is this possible. I think that he is hiding something serious from us. Maybe ulcers came first and then he leaves tobacco. How can we know that it is not a serious problem like mouth cancer. Suggest me some test or any other mean and where can we have these test.