IMO, it's weak case. reason below:
if you want to sur you, check the local lawyer and see if anyone is interested in your case.
if you do file in court, the court will ask you the damage, if your kid is disabled, that will be a completely different case, but it seems the injury might be minor (i might be wrong, you can tell in few days). you don't want to spend all your time and money for an apology.
As for discrimination, the law only states that it's illegal to discriminate on the bases of race, color, national origin, religion, sex, age or disability. not sure which category you are in. Did the owner say anything regarding anything above?
The best bet will be small claim court (up to &7500 in CA, I believe, limit varies in different states). yyou may get your medical bill back.