I have what feels like a hard knot that is not movable on my mastoid bone behind my left ear. I noticed this getting larger about a week ago with no pain. I have had sudden weight loss and nausea. I have severe trauma induced gastroparesis and have nutritional deficiencies and haveen very lethargic, vision in left eye changing and some neuralgia in limbs. I played it all off on nutritional deficiencies until this appeared. Could it be an infection or what might it be? No ear pain, no fever and no headache