Developed Breathing Congestion. Have Allergies. What Can Help Me Cope Them?

Hi im from Brooklyn, NY and have been going up to Long Valley New Jersey to visit my girlfriend every weekend. At first it was never a problem, until recently ive developed a breathing congestion everytime i go up to visit. I figured it was my allergies or something that I could be allergic to in her house. She lives in the country side of jersey where its mainly farmland, trees, and less air polution unlike NYC. Its hard for me to last up there for more than a couple hours since my breathing becomes very difficult. Almost like im sufferacting. Is there something I could take? I will be going up again soon and wanted to find a solution or at least a temporary one. I appreciate all advice and help I can get, thanks!