Hello User.
Ther are some possibilities.
Especially your posture during reading.
If you have cervical spondylosis it can cause vertigo when you stoop.
See if it is the same.
You can consult me at practo for proper Homoeopathic treatment.
Next Steps
consult through practo for proper treatment.
Health Tips
sit straight while reading and keep the book at certain level to avoid folding neck to much