I've got six hens that I got from a family member. Recently, we've gotten some strange eggs and I'm trying to trouble shoot. We got a tiny egg, sorry no pics, but it was the size of a grape. The next day we got an egg with no shell. I know my 2 RIR are older, maybe 5 years old? Despite having 6 hens, the most eggs we've gotten in a day is 3. So, any ideas on what's causing this? Are they just too old?