I have a Basset Hound and I use "Huggie Wipes (Simply Clean)" after each walk to remove dirt, etc. There are times where he will wake up and start wheezing. Here's what I do:
Get a Huggie Wipe or a Paper Towel. Fold it once. Take the corner and with your index finger on top, gently insert it into the dogs nostril about 1/4 inch. Press down gently and push the paper towel towards the outer nostril slit. Also look directly into the nose. You might find some hair, grass or whatever that could be irritating your dog. Then just take your dog outside for a few minutes of fresh air. That's always worked for me.
Basset Hounds are big sniffers. You wouldn't believe all the crap that I remove from his nose each time.
Good Luck !