I Have A Slightly Raised Rot On My Upper Collar

I have a slightly raised rot on my upper collar bone area. it started small about the size of a pea now has grown to size of a little larger than a quarter. It has just started to become itchy within the last week. I have had it for about 4 weeks. this is the 2nd spot to appear like this. the first one was on my breast that stayed for about 6 weeks same symptoms.