My Buff is 11 months old & appears very healthy. She started laying at 6 months &, until about 3 weeks ago, was laying perfectly normal eggs, but they were on the small side. The first egg in the group of 11 (shown in photo) was what she laid for 4 months. Then, all of a sudden, she started laying abnormal eggs. In the group photo, they were laid in the order shown (left to right). The one at the bottom was the last egg laid. I have 6 other hens, the same age, who have no problems at all with this. They have plenty of room &, up until a month ago, were fed Nutrena Naturewise All Flock & given plenty of oyster shell on the side. They are now being fed Nutrena Naturewise Feather Fixer, with oyster shell on the side. When changing feed, I mixed the two for about 2 or 3 weeks before giving them pure Feather Fixer. This is the only Buff Orphanton I have. The others are a mixture of White Leghorns, Dominques, & Barred Rock. Is this likely a defective shell gland or the hen's body adjusting to produce a larger egg? Any advice will be greatly appreciated.