I went out to the coop/grow out pen this morning and my little splash silkie hen was dead. She is about 5-6 weeks old. They have a heat lamp and it stays warm in there. I did notice she would shiver and not run around a lot like the others. I though she might just be lazy. All the other chicks she has been with seem healthy. I have looked all over the web for what it could be and wanted you opinion. Could it of been neurological? Vitamin deficiency? Marek's? Marek's they usually grow thin right?