Before suctioning, do nasal drops: 1/4 or 1/2 teaspoon of salt dissolved into one cup of water (google "nasal drops salt water" to find which it is). Let it cool first before administering, of course.
Also, use a humidifier, and take baths with him and keep that moisture in the bathroom. This will help a LOT.
These things will help at least as much as any medicines, and if it were me, I wouldn't put a drop of anything into his tiny body at this point. Much better that he be a little under the weather than have, say, liver or kidney damage for life (or a life-threatening situation).
Other than that, I would ask his doctor if offering cooled boiled water is a good idea, and how much - it is extremely important to avoid water toxicity (too much water). Just a little to us can be way too much to such a young baby.
Hang in there. Sleep when he sleeps! Let the house be a mess! Just be there for him and take care of yourself, too.
Oh, and I can't believe I almost forgot: if you nurse him, lay off the dairy and eggs till he's better. If you formula feed him, try soy instead of dairy formula, at least for now. Dairy (and eggs) make mucus much, much worse. The difference is *incredible*! You'll see a dramatic improvement within half a day or so.
L.