Cure to post nasal drip? Please help me I have been suffering forever!?

Hey will you please help me! I have this awful post nasal drip that I have had since October! I think it is caused by allergies, but I am not sure. I take allergy medicine and nose spray already. My mom has food allergies, and my dad is allergic to pets, but I think I might have an environmental allergy. When I go outside, my nose runs, and I am constantly spitting out mucus (not a good fashion statement) the mucus is white, although sometimes it is yellow in the morning. when my throat hurts, everything feels ok except for it. I really want this to go away, and soon! The most thorough and informative answer gets best answer! Also, how much do allergy tests and blood tests hurt on a scale of 1 to 10? Thank you so much in advance for your answer!
oh i forgot to add i use the neti pot too

try this

http://health.howstuffworks.com/home-remedies-for-postnasal-drip.htm