Hello there, I am dr.milan an infectious disease specialist answering your question. If you have chest infection than you need to go for certain investigation. One of prime importance is Culture report of your throat secretion, blood culture, Complete blood count. After that treatment protocol of your chest infection is decided, and complete resolution of your chest infection is needed. I need to know are you feeling well completely now? If yes and you have a spot on your knee that might because of some drug reaction but it is rarely. I think you follow advise of your doctor, it is mostly a bite. So no need to worry about that. But complete the treatment schedule given by your doctor and follow his advise. Hope i have given appropriate guidance to you. if you have any query you can consult me anytime. Give me star rating according to your satisfactory level. Thanking you.