Suggest Treatment For Pimples On The Back

I have a samll pimple on my back , just below left shoulder, few days back. it was paining and pin was felt over fron hand muscles also, I felt that the pus of this is squeeze out then it will be al right. But now there are sall-small many pimples have errupted near by the original pimple. They are paining and have itiching.