I have severe neck pain from an accident. Mri showed 3 discs involved in june 2012. The pain is a lot worse now. Should I have another mri?

Yes. If your pain is worsening significantly, you should get a follow up MRI to determine what, if anything, has changed. Depending on the results, additional treatment options may be available to you now. Good luck.
Not always. You should call your doctor. If you only have worsening neck pain then doing another image so close to your previous image may not change the management, however of you are having new neurological symptoms then repeat imaging is necessary. Please ask your doctor. Hope you feel better!