Little bump on back of ear popped it now feel sick and have a serve headache?

Abscess. There are a number of possibilities. You may opened an abscess (infection). The pain you are experiencing should be at that specific area in the back of your ear. An infected lymph node (gland) is another. An infected cyst is another. Never pop a bump in back of the ear. The infection may spread and cause a more serious infection. See a physician as soon as possible.
May be an abscess. May need to get checked by your doctor, you may need antibiotics, if you have such sudden symptoms.