His appetite should return in a week or two. Bring him in at night for awhile until the evening temperatures are warmer and the spring rains are gone. Sometimes tortoises wake up with a runny nose. A warm bath often clears up the problem. Dry the tortoise thoroughly afterwards.
Runny noses are a serious problem and there is no quick cure.
In many cases, there is no cure. We cannot advise you about exact preventative measures because even the most well tended to tortoises sometimes become ill. If your tortoise is ill or injured, he should be kept in the house. F. A clamp-on light with a 40 or 60 watt bulb is helpful. Give him extra vitamins at this time.