As you have seen soya especially in amounts you are takin will cause increased mucus secretion of all mucosas. The best way is to either stop taking soya based protein supplements
and switch to another.
if you cant. Try to reduce the amount you are taking.
Also Take Tab.Desloratidine+montelukast
1Tab at night just before bed.
i still reccomend you to switch your brand , you can try Sunwarrior or other whey or oat based supplements.