Anaphylaxis

Took my first Xolair injection Friday and 7 hours later went into anaphylaxis. My blood pressure dropped dangerously low to the point I was about to pass out right before I took Neffy. Difficult swallowing… the whole bit. Has anyone else experienced this or anaphylaxis in general and how long does it take to feel normal again? This was 3 days ago and I feel so tired and like my head is in the clouds.