Your eyes must be very fatigued and lack of nourishing. You know the way that rubs the eyes is not the proper method for you to cope to such kind of problem. When you rub your eyes, it is easy to get eyes infection with inflammation by virus. That is why your eyes appear red. Moreover, the strongly overdrive of your eyes muscle will broken the exquisite eye skin and blood circulation, that is the reason of black eyes happen. The best way to heal your dry eyes is to apply some physiological eyes drops to humid your eyes, then relax some time. Let your eyes look for a far distance and eat some food contains full of vitamin A and carotene. That will basically solve your problem.
Your eyes must be infected according to what you said. Itch, dry and red are big signs to warn you that your eyes are damaged. Now, you must stop rub them, which can only make thing worse. I do not know whether it can cause black eyes or not, but it can cause serious conditions than black eyes.
Go to the formal hospital to check out. If you have no time right now, use normal saline to wash eyes. Good luck!
It will not cause the black eyes which may appear because of the strong beat or the knock. After the knock, the blood circulation around the eyes will be blocked which will suddenly cause the black eyes. But you should not rub your eyes often which may cause the bacterium into the eyeballs. If you feel not comfortable in the eyes, you can go to see the doctor.