How Can Psoriasis On The Elbows And Knees Be Treated?

Hi I am 39 years old female and I have had psoriasis for years mostly elbows, and knees but I also have it in my hair and a few spots on each side of my breast. A few years ago I started getting these hard sores on my butt cheeks and was told there not pimples but kinda related to all my skinny issues. But more recently I have been getting these big sores around my chin , and chin bones they are painful when squeezing them nothing really comes out except clear liguid I have never had acne before and really don’t think this is that. Also when they start to heal they have hard scabs over them the bumps on my butt look very similar. Do you know what this could be it is really messing with my self asteem? Two years ago I lost 80 lbs went from a 16 to a 2 and now I’m feeling as self conscious as I did then please help me!!!