FeNO score of 300

Been hospitalised twice last year for severe asthma attacks. Been on a prednisone taper for a month and a half currently on 5mg and take symbicort twice daily. My asthma nurse has started me on another prednisone taper today after my high FeNO test. Had a blood test and Will be seeing her again on the 9th of feb. What could my FeNO score indicate and if steroids aren’t helping it what other options do I have? Also what could the blood test be looking for? I definitely have the atopic kind of asthma which also exacerbates my eczema..