Post nasal drip due to exercising in cold environments

Hi all. I just started figure skating this year but recently I have been having frequent coughs due to post nasal drip from the cold air I breathe in while skating. I have tried various ways to minimise the problem and although I have recovered from my cough, I still feel thick mucous draining down my throat. It doesn't seemed to happen all the time but more so in the morning, evening and night. I tried clearing my nasal passages with Flixonase nasal spray and breathing in hot steam which helps temporarily but it comes back a few hours later. Why would this happen? Is more mucous being produced by the sinus? I have tried taking horseradish with garlic as I heard that it helps but it doesn't seems to do any good. I'm not coughing now but I'm afraid that the mucous and phlegm would soon build up and accumulate in my lungs and cause me to cough again? Will that happen? What can I do to clear the mucous? Is there any other useful tips for my problem?