Historic Spuffy

I'm looking for a fic based in the 1800, I think, where there is a legend that Spike is a vampire, but in actuality just has a strange allergy to the sun and is completely human. Because of his allergy he does not go out side during the day, but only at night, thus starting the legend. Buffy is found either passed out on the side of the road, running away from home, or being chased. If any of you know what it is I will greatly appreciate it. Thanks!

Sounds like In The Dark With You by Moxie
Summary: The year is 1835. Elizabeth Summers is injured while fleeing from a forced marriage, but when she realises who her rescuer is, she begins to think she may have jumped out of the frying pan into the fire. Are the tales about the golden - haired vampire who lives in the old dark house on the cliff, true? Or are they just stories made up to frighten children? She's just about to find out!