What you want to do is get the crud OUT, not dry it up and keep it in there, which is what Benedryl will do.
You need pseudoephedrine, and guaiafenesin will help to thin out the mucus so that it can drain. The combination pill with these two ingredients is the aforementioned Mucinex-D. In most places, you now have to go to the pharmacy counter to buy this; it is not stocked on open shelves because pseudoephedrine is now something that you have to sign for in most places because it can be used to make meth. (Although I have it on good authority from a pharma chemist friend that pills that combine pseudoephedrine with guiaifenesin can't be used to cook meth -- go figure.)
Note that the decongestant ingredient that is now usually the only one stocked on open shelving is Phenylephrine HCl; don't waste any money on that stuff, because it is worse than useless.
Until you can get to the store, go for the hot stuff: hot peppers, preferably cayenne or habanero; jalapeno doesn't work as well. If you have any spicy food in the house, eat it, or order the spiciest Chinese food you can find. If you don't have anything else available, make yourself a cup of hot water and stir in as much hot sauce as you can tolerate, and drink that; it will help your nose run and get some of that gunk out of there.
Hope you feel better soon.