Find Relief from Sinus Infections Naturally

Sinus Infections and Ice cream: I do not know about the various brands of ice creams and their contents. However, my body is lactose intolerant and whenever I give in to consuming ice cream [of the homemade variety,no less], in a few minutes,I feel the nasal clogging. Has anyone been tested for lactose intolerance? Sugar and other foods that do not agree with my system affect my sinuses adversely.