For The Past Month I've Had Small Itchy Red Bumps

For the past month I've had small itchy red bumps show up on my stomach, forearms, chest and back. I went to the ER and they said it was eczema and gave me some medicine. I took the medicine and it started to clear up. Now that the medicine is all gone the bumps have returned. What are the little bumps and what has caused them? How can I get rid of them?