sorry to hear your cat is having a difficult time!
has Misty had hairballs before? how old is she?
the reason i ask is that sometimes a cat who seems to be trying to hack up a hairball, but never does, could have asthma.
i have two cats with asthma, and i thought that they were trying to cough up hairballs, except they never did, and they never had a hairball, ever.
turns out they both have asthma, one has it pretty bad and needs medication every day, the other one her asthma is milder and she is only treated as needed.
check out this link and see if what they describe sounds anything like what Misty is doing.
i hope it is only a hairball.... and for those, my vet recommends some butter or margerine (if she wont eat it, you can put it on her paw and she will lick it off)
what makes me think that she might have asthma is that you say she wakes up coughing, and this is a very common time for a cat to be having an asthma attack
see this site:http://www.felineasthma.org/symptoms/index.htm
for more information
and then, if you want to see what a cat looks like during an asthma attack, check out this one:http://www.fritzthebrave.com/gallery/inhaled.php#Videos
click on the video of Fritz coughing.
when i saw that video, i finally knew what was wrong with my cat!!! that is what he was doing.
i hope for your sake and for Misty's sake that she does not have asthma, but if she does, its best to treat it as soon as you can. untreated asthma can cause respiratory collapse and even sudden death.
not meaning to scare you!! just thought i'd pass this along just in case. i hope she poops soon
and that the coughing stops!!!