You know, isn't it surprising we have lymp node reactions in our elbow? Armpit or neck? Ya. To be expected but the elbow throws you off. You have one leg with fluid retention and pitting only. Is this when you wake up, when you are on your feet for a long time? They call this edema and there are many reasons it happens. You need to be examined for this. Yes, infection can cause all of this. But you will want to rule out anything serious. Blood clot in your leg for example being the reason for the swelling. So, see your doctor with this information and please come back and let us know what is going on!