Coughing when drinking water or juices

My father 75, had sdh last year and sepsis (aspirational pneumonitis and uti) this year. Recovered from them bt he is having cough when drinking water or juices or thin liquid. We make a paste of Solids mostly and give. And he doesn't cough with coffee or solids. How to solve this? He gets scared when he coughs?

Is it swallowing issue? Any help?