At first thought I would be thinking that you have too many sheep. That’s a second thought as well. The next thought is, what breed are you raising? I have Gulf Coast Native sheep. They came with the Spanish and have survived 450 years. They have a resistance to foot rot and internal parasites. I got my start of one ram and seven ewes late last summer. We had lambs starting March 1. There is only shade tarp and a couple of tractor supply dog houses that they won’t use. In short, they don’t get shelter. PS I’m in Northern Arkansas . Watch Greg Judy’s sheep videos about shelter