I think it is normal to not eat a little when they are teething - I didn't notice a reduction in my girls' eating, but I've heard that around molar time, kids go on "eating strikes" because their gums hurt.
That is just a phase. Both of my girls went through that. At 6 months, they just become more aware of their surroundings and becoming more mobile. I found that it helped to nurse them in a quiet, dark room. Diaper changes also becomes a battle, too. That's why they came up with those slip-on types