I would limit the biking and basketball for a few more weeks. In biking when you are slouched position you are taking up all the slack of the posterior tissues and fascia aka the thoracolumbar fascia that connects up to the cervical spine, then your skull. Staying in the slouched position could easily create a slow prolonged stretch which could cause lengthening of the tissues. Basketball would likely be fine, as your head is up and you're not straining the tissues much. In this case I would use the feeling of a pull or sharp pain as a reminder of when you're doing too much. Easing into basketball and starting casually would likely be fine. Thats my 2 cents.