How to get rid of the pain on the right side of the bottom of my spine?

Hello doctor,

I am a 25-year-old male, around 199 cm tall and 85 kg weight. I have been playing sports when I was young (volleyball, tennis, and basketball) and I was fit for a long time. However, since I started higher education (around six years ago), I tended to study in a semi-bent position in my bed. Recently, I started feeling a dull pain on the right side of the bottom of my spine, which persists until I either bend my spine upwards with a pillow or sleep.

I also have to note that I sleep on my side, with a pillow between my knees. When I walk, this pain in the side of my spine increases (I do not feel any unbearable pain, it is just uncomfortable), but I feel a sensation from that spot in my spine to the bottom of my right leg (on the back side of it, mostly). Does this seem like a common issue? If so, please tell me what exercises I can do to prevent my spine from going bad. I am in a period of intense exams, and I need some advice on how to stop this pain.