“Just really congested that I haven’t been able to breath at all through one side of my nose.”
It’s most likely a sinus infection. These can last for weeks or even months, and they can make you feel awful all the time! Like I said before, learn how to use a neti pot (with filtered water and sea salt, not tap water and table salt), eat really spicy food, get some exercise, take ibuprofen consistently throughout the day for a few days — these things really help.
I sometimes used to get them but when I went running that could be enough to knock it out — something about warming up your sinuses and allowing everything to flow. A neti pot several times a day if necessary can also be great, but don’t do it right before sleeping. I just had a sinus infection last week, and that (along with spicy food) was what cured it.