Flickering of ur eye may be due to over stress, take sound sleep atleast 6 hrs every night, reduce the brightness of ur computer. U can take mild tranquilizer at bed time.
Black spots in front of eyes may be due to virtuous floaters, try to avoid to see them, they will not harm ur vision.
Next Steps
If problem persists for long consult local eye specialist.
Health Tips
Try to take 5 minutes rest after 1 hr working on computer.