痛い
My knee hurts.
私の膝は痛いです
My knee has hurt since yesterday.
私の膝は昨日、痛いです
My knee has hurt since I went hiking yesterday.
私の膝は昨日登山に行った後から、痛いです
My knee has hurt when I go down stairs since I went hiking yesterday.
私の膝は昨日登山に行った後から、階段を下りるときに痛いです
The inside of my knee has hurt when I go down stairs since I went hiking yesterday.
私の膝は昨日登山に行った後から、階段を下りるときに内側が痛いです