There are several possibilities as follows: Traumatic injury, sebaceous cyst or adenoma, a scab from a self-inflicted excoriation (due to scratching), or dermal cancer (benign or malignant), and more.
If it is associated with his lower eye lid could be a meibomian gland adenoma which is benign.
I can't tell you what it is without seeing it, of course, and even your vet may have to perform diagnostics such as a skin scraping or a fine needle aspirate in order to get a definite diagnosis.
Since he is normal in every other way you may not have to take him to the vet right now. However if the mass enlarges, or starts oozing pus or blood or even serous fluid, or changes for the worse in any way you may have to take him to your vet. So monitor the lump for now, but please bring him to the vet if necessary.
The bump his still there today,same size, but he started to open his eye a little.
And yes the bump is located on his lower eye lid!
Is there anything I can do to help!?
I will definetly bring him to the vet but how long do you think I should wait before taking him there!?
I mean if it's still there on friday, but I don't notice any change should I still take him??