Can I Take Theraflu And Robitussin Be Given For Fever And Headaches?

Hello! I'm a 20 year old female and I've been sick with a fever since friday, and it has consistently stayed at about 102.7 to 103.5 until tonight, where it has spiked to degrees of 103.1 to 104.0.
I have taken Theraflu twice and Robitussin once since I've been sick, and they lower my temperature from 100 degrees to normal, but once it wears off, the fever returns.
Also, when I've taken Theraflu (when my fever's dissapated the lowest), the fever leaves but a very bad pain in my head replaces it, making it hard to laugh, cough or bend over and stand up too quickly. (The head pain goes away for the most part when the fever returns.)
In addition, when I go to sleep, two things occur: I wake up in the middle of the night with uncontrollable shivering and feeling like I'm freezing, which can last for quite a while; also, my breathing path becomes very narrow and dry - for the first thirty minutes of waking, it's hard to talk above a whisper.
Tonight my temperature is the highest recorded since I got sick (104 at times, 103.5 at others) and its accompanied by occasional heart pain.

What do I have - and how could I get it taken care of without health insurance? (I am not covered by any plan).