Unbelievable!

Yesterday and today, I gave Pinuki double the dosage of Doxycycline (300mg 2 times each day). Currently, she is having the worst nosebleed she has had since starting the Doxy in June. It is a unilateral - left-sided bleed. She has been bleeding for over an hour and a half. She has sneezed blood spatter and is bleeding onto the floor. Prior to the bleed, she was lying on her back playing with Kalu. When she turned upright, she sneezed and the bleeding began. There are gurgling sounds coming from her nose. I feel so helpless! What do I do now?