NY Personal Injury

What is the name of your state? I live in NY and have a question concerning a personal injury inflicted upon my child by another child. My 8 year old son was playing at a playmates house when another child from the area started a fight with my son, (verbal) my son ignored this kid (about 11 yrs old) and the kid ran and drop kicked my son in the side, my son ran home and told me, my eldest son contacted the family of the boy that did the kicking, and we 'let it slide' for the last (approx.) 3 months. My son still has the bruise from the kick, so I took him to the doctors where I learnt that the bruise caused a contusion (which is a bruise) on his kidney that will take at least a year or more to heal. If, in a months time, my son still has pain, the MD is going to order a kidney scan to see if any other damage is present. On other occasions the same child choked my son, hit him in the head with a basketball, knocked him off his bike.. etc. I went to the kids house and talked to his mother, on the last incident, and she said she didn't believe it to be true, and let it go at that. I contacted the mother of this kid this morning and she yelled, said it wasn't her problem, that because it happened so long ago, there wasn't anything she could do about it.. and wanted to know WHAT I wanted from her, that he son was sorry and wont do it again. She did get very nasty and hung up on me, of course not taking any responsibility for the pain inflicted upon my child by hers.

Now that I gave a bit of a background, my question is: Do I have a legal standing to sue? And if I have a legal standing to sue, what type of Attorney should I contact?

Thank you in advance for any information you may provide.

Joanne