No, the vet didn't suggest a vitamin drench. We did check her teeth - 6 and all in good condition. I think a chronic case of fluke is a possibility, yes (although we're not actually in a flukey area). She was a bought in sheep so we didn't have her background. Out of the three we bought including her, one is fine, and the other died from pneumonia. So I thinking perhaps their previous owners weren't quite as scrupulous about vaccinating and dosing as we are, and they may have come to us with existing problems. Who knows. But I think I'll be more choosy about where I buy in sheep from in the future!