I've got omicron and I am very sick right now I don't know why I am so sick I had extremely powerful immune system
Rituxan kills white blood cells ( al those that have CD20 receptors), so that your immune system is less reactive. It may help for auto-immune diseases, but it leaves you with less defense against infection. That is why Omicron hits you hard - you no more have your "extremely powerful" immune system.
Your specialist surely talked to you about this before starting the treatment.