Social services/police investigating me!?

in a nut shell the SS decided i was the more practical parent after my break up with my ex girlfriend we have 2 chilren and she is going through a hard time!! so last week i dropped my boy of 4yrs off and didnt see him for 5 days, when i returned the SS had seen my son and noticed a bump on his cheek so they sent him to hospital for a check, he obviously had an injury but now ive been told i cant see my son or daughter till the investigation is concluded!!! the reason i cant see them is because my son said "daddy did it" which obviously was a little fib, ya see my son has done this a few times and has a bit of a habit at doin it, he said the same thing just last week after he knocked a plant pot off the wall in my mums garden, "daddy did it" when i clearly didnt!! the saught of thing you take with a pinch of salt!! now im in a position where i cant see my son or daughter which is laughable! ive fed, watered, loved, cared and learned them good morals and manners for 4years and now social see me as a threat however temporary this is i just dont know what to do! ive been compliant but they dont understand how pathetic this sounds!! my kids are my world id feel sorry for the person who ever layed a finger upon there head! why are they doing this! so basically im now in a position where im being investigated by the police through absolutely no fault of my own!! what the hells wrong with this country! its maliciuos!!