Unless she's eaten a roach/ant bait, the sprays shouldn't effect her like this.
Cough that produces retching, phlegm or froth may be indicative of alveolar disease or pulmonary edema.
Whether this is your girl's problem or it's something else - when any dog has symptoms like you've described, they need to be seen and evaluated.
Please never delay getting treatment for your companion. Remember, animals hide their illness and injuries as long as they possibly can (it's a survival instinct) , so when you notice something's wrong, it's probably something that's been wrong for a while.
If you need help with care expenses, here are some options:
Pit Bull ? http://www.pbrc.net/fund/financial.html
Also, call your local Humane Society for options and low cost clinics. If you have a Pet Smart or PetCo in the area, they usually have rescue organizations working through them (not a part of them) and they may be able to provide some help.
Good luck with her, God bless