I am 17 weeks pregnant and i am suffering from cough and mucus my doctor prescribed dexamethasone injection 4mg after that i got shocked,shortness of ?

Unclear: I'm unclear why your doctor gave you a dexamethasone shot for cough and mucous? That isn't standard treatment. A decongestant and nasal washes would be a recommended treatment for what you describe. I wasn't sure you what you meant by shocked, shortness of? You had shortness of breath? I think you should see your doctor again for clarification of his/her recommendations.