Hi Tina, the most important thing for you to do is get an X-ray and a doctors exam. Since you can't afford it, I will make some suggestions as I did the exact same thing years ago and did not have insurance as a poor college student. But please be clear that if does not get better after several other things I suggest, go to the ER, many hospitals DO treat people without insurance and have a fund that will pay for it. So remember, you always have that option and should probably do it.
     There are several things that may have happened to your knee when you fell. You could have torn a ligment or a tenden. You could have a severe bone bruise that could heal in time on its own. I hope so as that is the easiest to do without a doctors help. The most important thing to do is buy a cheap knee brace or a large ace bandage. MAKE sure it is not to tight as it will cut off the circulation of blood you need to help it heal. You need support, this will help with the pain. Second, take by directions on the package an over the counter pain relief that has worked in the past. IF you are unsure, ask the pharmacist to help you select one that is right for you. Extra tylenol or aleve might so the trick, or tylenol pm will help you to sleep. Tell the pharacist in detail what happened and where it hurts. Don't over use the knee by activity. You could also use a cane for a few weeks to add support and take the pressure of walking off the knee. Put a pillow under your knee when you are in bed or watching tv. Use heat to help the pain, ThermaCare is a product that sticks to the body and works for hours, gently. Sometimes ice feels better, but don't burn the skin by using too cold or for to long. But heat may be better since the injury is several weeks old. Rest and careful use will help it to heal. I hope I have helped you..if you have any questions, please contact me. Good luck and feel better.