Can you describe the fitting a bit better? Not sure that fitting relates to clostridial problems, although quick death does.
We noticed a 6 week old lamb rolling about on the grass, as if fitting, the other day. We observed it, and it seemed to me that it was a stomach problem, rather than a mental one, and that it might be a little bloated, although not unduly. We caught it, jabbed it with a/b, gave it some lamb quick start, also some bicarbonate of soda diluted, and, for good measure, some liquid paraffin. Kill or cure, we thought, as we had not seen anything like this in 15 years of keeping sheep. Half an hour later, she had recovered, and 3 days later, no further problems.