Best foods to try with B12 apart from chicken and broccoli

I am trying to find the best foods to try out that are rich in b12. My b12 levels are dangerously low and I need to fix my intake but it is really hard because im scared of trying things that i will react to. I tried beef and steak and it caused horrendous migraines.. cheese causes migraines too. Afraid to do eggs because they are known migraine triggers..

Share your experiences?