From the description of your symptoms it sounds like you may have a joint effusion, which is exactly as you describe: fluid that goes to the joint. The question in this kind of situation is what is causing the effusion. In order to figure this out, the best thing for you to do will be to see your primary care physician
right away for an evaluation. He or she will of course want to evaluate your elbow and possibly drain off some of the fluid to look at under a microscope and send off for further testing. This may also help you feel better without all of the swelling that makes it hard to use your arm. However, since there are many things that can cause joint effusions, your doctor
will also want to ask you a lot of questions. It will be important to know if there has been any trauma to the area; if you have noticed any pain in the elbow or other joints; whether you have been having any fevers, chills, night sweats, or weight loss
; any rashes or changes in your skin; or any new activities. Examining the joint will also give your doctor a sense of whether or not there is concern for infection which can be quite serious in a joint. Again, please discuss this issue with your doctor.