I'm presuming that you mean 'when I feel inside the swelling I can't feel any bone underneath'?
Try not to worry. When you hit your head hard, one of three things can happen:
- Your brain moves backwards, forwards or side to side in your head, and you get bruising or bleeding in your brain. If this happens, you would have signs (observable things to the person examining you, that are different from normal, such as unequal pupil dilation) or symptoms (things you experience that are different from normal, such as headache, confusion, etc) of a head injury.
- You get bruising or bleeding in the outside of your head, with or without damage to the skull bones.
- Both.
The person who saw you would have checked you over for 1. You are also typing coherently, don't sound confused, and don't mention any symptoms that give the impression that you are very unwell (although the internet isn't a good way of deciding, so if you think you are, get help).
However, you say your forehead is very bruised. Foreheads have a very, very good blood supply, and they can bruise spectacularly. They also get very 'boggy' when you damage them. In other words, they swell quite impressively with fluid, much the same as your knee can when you fall over. That swelling and fluid can move down around your eyes, too - it's just gravity and the way your body absorbs it.
But back to your 'hole'. Because your forehead has swollen up, it's got very puffy and boggy. So your bones in your eyebrows, etc., which are very small and delicate, will be really hard to locate with your fingers, because it's like trying to feel them through an inflated swimming pool arm band. There's no hole, it's just that the skin over that area has been overinflated. Put some frozen peas in a plastic bag and wrap the bag in a tea towel, then gently hold it over that area. It will help to take down the swelling.