Recommend a OTC cough medicine for a increasingly violent cough

Patient: I have a cold or flu and a persistant cough that is becoming increasingly more violent as my throat continues to be “itchy”, the phlegm is green and thick but nose is not blocked. What OTC medicine can I take to surpress the cough and that is immediate? I am looking for something very strong but not necessarily one that would make me drowsy. I have tried delsym but it is of no use. I have now been resting for a week. As I am overseas I can’t afford the cost of visiting a GP. Please help!