Omalizumab - when xolair stops working?

Iv been hive free for the first 2 months after my shots but 3rd month I noticed patches of hives come in and go. Today is 2 days after my 4th shot and im covered and miserable with hives. No ryme or reason nothing different! Iv been on benadtyl and zyrtec this past week on top of getting shots and i only see more coming in .. Iv noticed my hives are fully active starting in the evening and worst all night. Im praying it will all be gone like the first two months ( it was a miracle for me to be hive free) .. I hope your hives are better now . I just wonder if we become immune to it?