A. The antibiotic treatment was probably not successful, you will need to take a urine sample and your vet will have to send it to culture and sensitivity in order to check to which antibiotic those bacterias are sensitive to. it will come back a few days later with a result and a new antibiotic treatment will be prescribed.
The phlegm spiting sounds like coughing, it could be kennel cough or some other lung or heart issue.
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