Had antibiotics for walking pneumonia for 6 days. Cough is back. What do you suggest? Ashtma?

Asthma.. ..Is one of the nost common causes of persistent cough, so it certainly is possible. I actually doubt you need more antibiotics. Sometimes cough from a respiratory infection persists long after the infection is treated.
Pneumonia. May not yet be gone--check with provider, may need additional treatment.