I was born with extremely dry skin, so I know all about pimples. I usually get these pimples, like yourself, on the back of my upper arms which gets a good weekly scrubbing with the rough side of a friction sponge, followed by a good slathering of petroleum jelly before bed. It may also be caused by friction from clothes, the constant rubbing from clothes will further dry the skin possibly creating a pimply feel. In my case, if I gain any weight, I will experience a pimply stomach, I treat this in the same way. It works for me and I hope you try it and get smoother skin. Age may play a part in this due to our skins becoming dryer as we get older, you and I are of a similar age me being 52 and well into the menopause, another contributing factor. You, I'd imaging that once the nicer weather arrives your skin will improve, because we all get more air to our skin from wearing less clothes. I could go on, but for fear of 'going all on', I won't, but will you let me know how you get on with the friction sponge and petroleum jelly.