Coughed or sneezed?
At times, a forceful sneeze or cough
a blood vessel under membrance of the eye
It is rather common and often causes no pain, only a scary looking eye. Often resolves completely w/o problems. Sometime, there is quite a bit of blood causing a thickening area and thus one can feel something there during a blink/eye movement etc...
If u r concerned, consult doc. Good luck.