How can I tell if my whiplash after a car accident will get better?

Evaluate first. Surgery complication rate anything from40-7o % cervical lysis procedure facet diagnostic blocks if indicated. Followed by radiofrequency ablation. In combination with neural flossing exercises. Best long term results.
Warmth and time. A whiplash is a strain of the muscles of the neck. Like any muscle strain, it requires warm therapy(compresses), massage of the neck to relax the muscles, and time. Also, comfortable positions during sleep and avoiding strenuous activity will quicken the time to healing.
Can't. The best answer is how soon after getting whiplash symptoms before you started therapy, the severity and strength of the collision, and your motivation to follow through with exercises, etc. If you have started therapy. Even with all of that, each individual reacts differently to therapies and time frames. I f in doubt, get a second opinion.