Knee injury opinions?

so about 2 months ago i dove on turfed concrete (for softball) and all i landed on was my left knee... it bruised and swole but i didnt rlly care. The swelling went down but there was water on my knee(im used to that) but everytime i touch my kneecap it has a sharp pain in a certian line shape that starts at the middle bottom and raps curved up the inside....... this past monday i droped my knee on a girl sliding home, the swelling and bruise are returning. My dad thinks i have a deep bruise from the first incident and the water is pushing on it causing it to hurt. Is he right? im gunna go to the doctor sooner or later i just wanna get some opinions on how serious it is. thx much if you have a helpfull answer ^_^