What Causes Itchy Bumps On Elbows, Knees And Feet?

Hi, i keep getting small itchy bumps on the boney areas of my body. (Elbows and Knees and now the top part of my feet.) they and feel like mosquito bites but if i itch them it spreads and when i put lotion on them it seems to also get worse. Any ideas what this could be? I have been treating it with itch ointments but this has been going on since December and ive gone thru 2 bottles already....