Hi Alexandra! Welcome to the community here. 🙂 I just searched in Youtube with this search term “violin hand stretches” https://www.youtube.com/results?search_query=violin+hand+stretches. It shows many videos with good stretches. i can’t link you to one specific video because what helps you may be different from what helps other people. But I would suggest to watch some of those videos, try the stretches and go with the one that feels most comfortable for you.