I recovered from a cold a month ago, but there's still a lingering cough, sometimes when i speak but mostly at night when i sleep. what can i do?

Possibilities.....: This could be related to bronchospasm which can occur after an upper respiratory infection or bronchitis. Both bronchodilator and steroid inhalers can be used to treat this, if present. Another possibility is post-nasal drip and there are effective steroid nasal sprays that can treat this. So, see your doctor to determine the precise etiology of your symptoms so treatment can be rendered.