I was drunk saturday night and fell over a metal beam while running, iv grazed my little finger REALLY deep...

its on ths joint near my knuckle and it really hurts when i bend it..thing is though it hasnt scabbed yet..well it has kind of but theres like a small chunk missing outa my finger and its a yellowy greeny colur...is this normal? I cant get it check out because if they ask how I did it I cant tell thm, my mum thought I was at a friends (im 16) and I said I fell up the stairs. Also it was weaping until a couple of days after...do you think its infected? i was outside till the early hours of sunday morning..my mum is suspicious about it as i was complaining about how much it hurt and she said to me are you sure you did it on her stairs..you wernt outside anywhere? ..but this could be because of recennt events wher shes found out ive been goin out drinkin when im "at a mates" and it could just be a trust thing..