Can Using Nasal Spray Cause Severe Nosebleeds?

Had a sever nosebleed gushing out of mouth and down my throat on sun., took 35 minutes or more to stop. Went to my allergist the next morning who send me to ENT who cauterized it. He did not give me any post instructions - just told me to use saline and Bacitracin for two weeks. I cannot believe how painful it is,,,he said to take Tylenol. When I look up with a flashlight there is all yellow and black stuff there, gross. Normal? To be expected? When will that come out? This is the first nosebleed I ever had. I have allergies and use nasal sprays which might have caused this.