Does Flesh Ward prevent Stamina loss from one source multiple times?
Page 7 of the Arkham Horror FAQ
says

Q: When exactly can Flesh Ward be cast?
A: When you are told to lose 1 or more points of Stamina,
you may cast Flesh Ward to prevent that loss. For instance, this can work on the Stamina from a single failed Combat check. This does not make the investigator immune to fur- ther harm from that source, it only prevents it one time.

The answer appears to be that 'one source' implies one singular event, like a single attack from a monster.