Neck Strain During Overhead Barbell Press

I've been training for over 3 years and always stick to weights within my limit. Yesterday, during my last set of overhead barbell shoulder presses, I pushed to failure as usual. On the last rep, I felt a slight pain in my neck. Later, it worsened, and now I can’t move my neck properly.

I’m confident my form was good, but I might have unknowingly compromised it in the heat of the moment. Could this strain be caused by poor form, improper breathing, or something else like gastric issues?

What’s the best remedy for this? Should I take complete rest, It has got a little better today but the pain is still there and I can't completely rotate my neck, but it's bearable. Can I still go to the gym for light cardio or other exercises