Weight loss is not necessarily a problem. It's the proportion.Yes he possibly has got cold , he's indoors now so hopefully he's going to pick up . I'll get him to vets as well . I weighed him tonight and he has lost weight too
What kind of UVB bulb are you using? Please post a picture. The coiled bulbs are know to cause eye problems. Are you soaking your tortoise daily in warm shallow water? Also substrate with sand in it can cause eye irritation and also intestinal blockage.