The ABO blood groups are complicated. There is good evidence that inheriting some combination of them can be a risk factor for some diseases - see http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3827391/ for a discussion of this.

"Could it be the chicken and the lectin?????"
I doubt it - chicken is a good source of protein and I don't know of any evidence that alleged chicken lectins can pass across the GI tract and lead to adverse health effects for people with the B blood group or any other for that matter.

"Dr. Peter D'Adamo"
In my opinion D'Adamo is not worth taking seriously - he promotes a fad diet. This link (and links therein) may help NT readers to draw their own conclusions about this; https://en.wikipedia.org/wiki/Blood_type_diet.