Suggest Remedy For Itchy Spots In Chest & Leg

Hi I am 16 and I have lots of small itchy spots all over my legs chest and are spreading onto my back. They are also on my shins and behind my knees and in my elbow creases. I had excema when I was around 5 quite severely but have never had it since. They are very itchy and sore when touched. I also have one large puss filled spot on my elbow which is red around the outside of it and was wondering how to get rid of it. I have no medical conditions and am 5'6 and 48 kg