Post nasal drip is basically just mucus. So with spring allergies you tend to notice-- basically, it's your body's reaction to something foreign. So when you produce a little too much mucus then ...

Post-nasal drip, a common condition where excess mucus accumulates in the back of the throat or nose, can cause discomfort and various symptoms, including coughing, throat-clearing, and stomach upset.

Symptoms include a post-nasal drip, stuffiness, sinus pressure, facial pain, and frequent nosebleeds. It sounds like it could still be just a cold, but if these symptoms last more than 10 days ...