I actually ate chicken in my first week of confinement. It was on the menu of Natal Essentials, where I ordered my confinement food delivery from. I did not suffer any side effects.
Each meal came with pork, fish, chicken and vegetables. It's more important to eat a wide variety of foods than to restrict yourself. Most of them are just hearsay.
If you had a c-section, do avoid shellfish as it is said to make the wound itch.