hell spell? what do you mean by that? a curse or something?
animals make noise when something scares them, or they see something as a threat, doesn't mean anything. an eagle flying in the sky doesn't mean it's following you, its nest could be nearby. a lot of the time, these things are in our head. the spell might not of even worked, but you're so scared it did, you're hyper sensitive to things and are adding up everything that goes wrong to the spell. remember 'its not the power of the curse but the power we give it.' if we convince our self things are bad, chances are things will get bad, so don't worry too much.
it could be the threefold law, or the spell backfired [since i have no clue what you cast] if you're worried, do a cleansing and cast a protection spell. if it's karma, this won't do much, but it's all i can think of without knowing the spell.