A black eye is a relatively common result of injury
to the face or the head, caused when blood and other fluids collect in the space around the eye; swelling and dark discoloration result-hence, the name "black eye."
Most black eyes are minor injuries that heal on their own in a few days with ice and pain medications.An ophthalmologist should examine the injured eye to make surethat no significant injury to the eye has occurred.
There doesn't seem to be any problem with you as already two days have passed and there is no complication like
Changes in vision
Signs of infection
Behavioral changes, forgetfulness, or lethargy
If any of these symptoms arise,consult the doctor immediately.
This lump is not to be worried and would shrink slowly and of its own.