Suggest Remedy For Congestion In Lungs

Hi. A few weeks ago I was sick with what felt like a common cold. It went away in a little over a week. I felt better for a few days, but after that I have just felt kind of non-descriptly shitty. Let me explain: I don't feel like I'm very sick. I'm not feverish. I'm just mildly congested, with a feeling of a light drip into my lungs that causes me to cough. Sometimes I'm coughing a bit of mucus, but that seems to be coming from the back of my mouth/throat and not my lungs.Also, I'm 21, 5'10, 185 lbs. I don't have a history of allergies that I can think of. Do I have a nose infection or something? This isn't awful, it's just been around for a non-negligible period of time and is annoying as hell. I want to feel 100% again. Thanks