What Causes Swelling, Redness And Soreness In Knees?

hello, i am very scared i may have something seriously wrong. my knees where bothering me swelling, redness, liguid, now my whole body aches my throat got sore now i am hoarse all the time i got acouple nots pop up in the back of my neck around my hairline now it gets really hard to hold my head up sometimes back kills me what is wrong with me