Similar thing happened to me around the same age. I got reported by some kid who said he had saw me handing ecstasy pills out to two of my mates in school. In actual fact I had got tic tacs in my hand and was just handing them between my friends. Next morning a letter addressed to my parents drops on the door mat saying I was not allowed back in school because I had been accused of dealing and they were investigating and getting the police involved.

Although both of my mates both instantly confirmed they were mints and nothing like the accusations went on, the teachers argued they would say that to avoid getting in trouble themselves and their parents getting involved.

Took about two weeks and 6 or 7 meetings with the head teacher and the police were called in to speak to us all together with our parents present before they finally accepted it and let the issue go.

Still it caused a whole load of problems at home and in school after though. As soon as doubt has been cast it's not something people forget quickly.

Biggest thing that still really annoys me about the whole incident was they would never tell us who had reported it. I still wonder who it was occasionally...

All I can really say is don't let your kid feel like trust has been damaged between you and them. It sounds pretty obvious but it took a long time for me too stop feeling that was the case with my parents and that sucked worse than anything else.