If you had Dermatophilosis ( rain scald / fleece rot / rain rot ) you wouldn't have a lovely fleece and a healthy skin . Interesting that all your ewes are loosing wool , wonder if they have shedding genes ? if you see wool in their mouths or persistant scratching /rubbing then as Marches says get the vet to skin sample . In the second picture she now looks about perfect condition so 200gms a day for twins spot on