Well, first of all, let me say that I DID do a search first and came up with tons of stuff about congestion issues when vaping. The problem is I ended up more confused than ever. It turns out that: 1) Some people are allergic to VG. 2) Some people are allergic to PG. 3) Some people are allergic to certain flavorings used in the e juice. And finally, 4) Sometimes people just get the flu/allergy when they are vaping and there is no connection between the two whatsoever. Jeesh! 
Now, here's a little bit more detail about my situation. I've been off cigs for over a month and a half. Almost all of my juices are about a 50/50 blend, with a few leaning more toward the VG side. I've only really noticed the increase in congestion in the last couple of weeks and just realized that it might be related to the vaping. Since there seemed to be more people who reported problems with VG than PG, I went to the vape shop today and got some juice in a 70/30 PG/VG blend. I figure that this will allow me to rule out #1 and 2 above. If things get better, it might be a sensitivity to VG. If it gets worse, it could indicate a sensitivity to the PG. If there is no change, then I will probably assume that it's just an allergy, since this is allergy season, after all. I have always had allergy issues, but have always felt that smoking cigs helped me with allergies, since I was putting so much tar and other gunk in my lungs that I figured the allergens couldn't get in as well. I suppose I could go get an unflavored juice and rule out out #3 as well, but I consider this the least likely of the four possibilities.
Do you think I'm approaching this right? Any other suggestions?
Thank you in advance for your help!

Now, here's a little bit more detail about my situation. I've been off cigs for over a month and a half. Almost all of my juices are about a 50/50 blend, with a few leaning more toward the VG side. I've only really noticed the increase in congestion in the last couple of weeks and just realized that it might be related to the vaping. Since there seemed to be more people who reported problems with VG than PG, I went to the vape shop today and got some juice in a 70/30 PG/VG blend. I figure that this will allow me to rule out #1 and 2 above. If things get better, it might be a sensitivity to VG. If it gets worse, it could indicate a sensitivity to the PG. If there is no change, then I will probably assume that it's just an allergy, since this is allergy season, after all. I have always had allergy issues, but have always felt that smoking cigs helped me with allergies, since I was putting so much tar and other gunk in my lungs that I figured the allergens couldn't get in as well. I suppose I could go get an unflavored juice and rule out out #3 as well, but I consider this the least likely of the four possibilities.
Do you think I'm approaching this right? Any other suggestions?
Thank you in advance for your help!