You have to start conservative treatment and the cause of your disc prolapse can be due to this incident or it can also be due to any past wear and tear of your thoracic spine.
You should strengthen your back muscles by proper regular exercises. You should follow proper ergonomics in your daily living. Sit on proper chairs, sleep on proper bed and use proper footwear. Avoid horse riding, riding on motor cycles and all activities which can increase problems of your spine.
If your symptoms progress then you can start taking NSAIDs, consider steroid shots and also consider options for surgery.
Discuss with an orthopedician and explore all options.