How much is she passing though? If it's only a little bit at a time, it could just be residual stuff from the enema itself, and not because the impaction has loosened significantly. I don't want to sound skeptical, but that does happen with impactions, not just with horses, but people, dogs, cats, etc...what is passing looks like diarhea, but isn't. I would inquire with your vet about getting another enema done, as well as tubing her, or running some IV fluids into her...she is probably extremely dehydrated at this point, even if she is drinking some, due to the impaction, and the fever.
Regarding the strangles, I think you can get that fluid tested. Are her glands in her throat area swollen? That's usually the biggest sign of strangles, is the glandular inflammation. She may have influenza or someother type of viral infection though, which could be primary or secondary to the impaction.
I would blanket her, atleast lightly, as well, just as a precaution; keep her warm, so her body isn't any more stressed than it needs to be.