The boy with the black eye.

So I am a preschool teacher. I love my job and it comes with many rewards. But it can also be extremely stressful. Here's my situation of the month. I have a one year old super cute young boy in my class. He's very friendly and loves to cuddle! For the past month his Mom has been in Italy. Dads in 21 days and out 21 days therefore it's up to grandmother to watch all three of their young children.
Grandma doesn't speak a lick of English 😬😭
2 weeks ago he came in with a busted forehead. Last week he had a busted lip. This week he has a pretty decent black eye. Her story is he was walking up the slide, lost his balance, then hit his eye... believable? Not to me. I then took a picture of the boy and sent it to my boss explaining to her the story behind it and that he's been coming to school with bumps and bruises for the past month like religiously! She responds "wtf?" I don't know what to do with that response. I pondered. Tell the parents. Run the risk of the grandmother going ape on me for snitching, ( which by the looks of the little boy I wouldn't put it past her) or just letting the parents find out when the kids reach them in Italy. Both sound like pretty crappy situations but my heart was settled on letting the parents know. I texted Mom and dad. Mom was livid. And dad knew about it but seemed almost relieved that he didn't have to tell Mom about it in person. After a little while Mom calmed down and was just anxious to see her children again.
I think I did the right thing by informing the parents. I don't know whether it was intentional or the grandmother just wasn't watching that poor little boy but one things for sure I'm going to feel 100 times better when he reaches his mom and dad on Wednesday ❤️
What would you have done?