What's this lump in between and on the side of my ?

I found this sort of lump or swelling thing on the side of my right and in between my . I don't know what to do about it. It just came all of a sudden a few days ago. I guess it's kinda lumpy, but it mostly feels hardened, i guess. It's kinda reddish and it hurts. I was thinking that maybe it was a bug bite, but I'm not sure. I want to tell someone after a week, because I was hoping that after a week it would go away or at least the pain would subside. After a week I was going to tell my grandma that I have it. I'm only 14 and I really don't know what to do. Should I wait the week or tell someone right away? Should I be worried?