Hi @igotz99problemz this is a very common problem! This can be an indication of over-exertion, sitting for prolonged periods, or insufficient hydration. They can rarely be caused by certain medical conditions, but these are rare and in most cases no cause is found even after tests. If this becomes a common occurrence despite rest, hydration, and stretching, then you may want to see a GP for a review and consider a general health screening. Feel free to arrange a teleconsult with me via the Doctor World application if you would like to have a more in-depth discussion.