my dog started coughing around 2 months ago. took her to the vet. got antibiotics for kennel cough and a steriod. after giving both for 2 weeks, we stopped the steroid and continued the antibiotics. the cough came back. the vet then treated her for allergies w/ an antihistamine. seemed to help a bit. we had changed her food around the time she started coughing, so we changed it back. shes still coughing, and im tired of throwing money at this. any suggestions?