What Causes Soreness And Indent On Top Of Head?

Today I lifted a heavy table at work with a co-worker. He suggested that I use my head to help disperse the weight, but right away the table started to press down on my skull. After roughly a minute of this we were done moving the table, but the top of my head was sore to the touch and had an indent. When I asked someone else to feel it they said they felt nothing, but every time I touch it I feel a clear indent. I have had no headache or other symptoms of injury, but I am not sure how long the indent will take to heal back outwards or at which point I should consider seeing the doctor. Advice?