I had a cold about 6 weeks ago and since then I have had a dry cough. Do you think it could be asthma?

Whilst cough is a symptom of asthma, everyone who coughs does not necessarily have asthma. Sometimes cough persists for few weeks following a viral infection. However, if one develops other symptoms, such as wheezing, or the cough changes, one must consult a doctor. Sometimes, cough is the only symptom of asthma (e.g.: in cough variant asthma), so if the cough persists for a long duration, one should consult a doctor.