Multiple egg quality problems, could winter cause it?

I wasn't having any eggs problems until January. I live in SE TX and the winters are usually mild, but this time around it gets to the low 30's and it has been rainy and windy. I only have 4 pullets and they are 8 months. They are also laying a lot less, last month i was getting 3 or 4 eggs a day, now i get 1-2 or zero. I get a normal egg maybe every other day if a get an egg, but most of them have issues. I have gotten shell less eggs, eggs with minor calcium deposits, i got one wrinkly egg, a couple of eggs with white sacs around them, and a firm opaque white odd shaped sac thing (im thinking a lash egg type thing, but its looked like egg white inside), and a small perfectly round golf ball sized translucent white sack with an egg white inside. They have also laid a few from the roosts, and i found a couple on the ground, which is not normal for them.
I think the winter is causing it. They have no signs/symptoms of respiratory illness, but it seems like it could be IB, I had a 5th pullet who was euthanized on 12/1/15, she got sick on 10/27/15 with what I suspect may have been IB after getting some help/information on here. Maybe the other pullets have gotten it. Does IB live on the ground that long? Maybe they already had it? They are all eating and drinking very well. they forage and aren't lethargic at all. Edit: I have also noticed quite a few small fluffy feathers under the roosts and on the ground a lot which is also not normal.

It isn't winter. I and others have had chickens lay when it was -20f and much lower.
The slowdown is due to short days. When your birds go into their second autumn and each thereafter there will be longer winter breaks without eggs.

As for the funky eggs, it is likely a respiratory disease but could be nutritional.
A healthy chicken's shell gland should work properly regardless of temperature.

Describe exactly what your birds eat: calcium and protein percentages, amount of scratch and treats as a percentage of total intake and if they free range, the quality of the forage.

Right now they are eating Purina Layena: Crude Protein, % (min) 16- Crude Fat, % (min) 2.5- Crude Fiber, % (max)6.5- Lysine, % (min)
0.7- Calcium, % (Ca) (min)3.25- Calcium, % (Ca) (max)4.25- Phosphorus, % (P) (min)0.45- Vitamin A, IU/lb (min)3000- Vitamin E, IU/lb (min)12- Methionine, % (min)0.3- Magnesium, % (Mg) (min)100- Sodium (Na) (min)0.3- Sodium (Na) (max)0.8- Phytase (A. Oryzae), FYT/lb (min)227

They also eat texas naturals: Crude Protein (Min) 18%, Lysine (Min) .80%, Methionine (Min) .40%, Crude Fat (Min) 3.0%, Crude Fiber (Max) 8.0%, Calcium (Ca) (Min) 3.0%, Calcium (Ca) (Max) 3.5%, Phosphorus (P) (Min) .50%, Salt (NaCl) (Min) .50%, Salt (NaCI) (Max) 1.0%
Which ever one the store has at the time. I also started offering crushed oyster shell last week. They have a good amount of space to free range, my property is 7,700sqft, and my house is only 900sqft and garage and patio is about 600sqft and i have a tiny front yard, so they get every where else to run round. There some grass, not a lot right now, but they eat that and bugs they find. They haven't had any scratch since early December, i ran out and decided just not to get anymore because that's all they wanted to eat.

edit

I hope it is a nutrition problem, but since they eat a lot, it shouldn't be. I don't want to believe it, but i know deep down its IB. I read there's nothing that can be done about it, you can only get rid of your flock and disinfect everything, and that the disease should die within with a few weeks. I am just going to keep the girls, i hope they dont start having respiratory issues though, hopefully their eggs will get better too. I'm so bummed I wanted to hatch chicks, and watch them grow with their mom, but even if i find some good eggs from them they will be born with IB if they make it. I thought i was really unlucky but i read that IB is actually a common disease, so it looks like a lot of people are unlucky. **** it, why must there be so many diseases, every living thing has to die one day anyways, we dont need diseases making living anymore difficult than it already is!

Infectious Bronchitis?
If one bird had it the others may also, they can carry it without ill effect,
so if not showing symptoms and eatingdrinkingpooping OK and active, they should still be able to lay OK.

Any chance they got into something toxic(man made or some plant) out in range area?

I would confine birds to coop and run for a couple weeks for observation.

I cant think of anything toxic that could be around. I will look around though. I will keep them confined to the coop and run, hopefully i will notice something