Will an MRI show a herniated disk even after the pain has gone?

It may or it may not. As disc herniations have been shown to shrink in size or resolve over time as demonstrated on sequential mri's over a period of 6 months 60% are smaller or not demonstrated any longer in persons who had sciatic symptoms, also realize that asymptomatic people with MRI can reveal a disc herniation and sciatica can occur without a herniation with other sources for the pain.
Yes. However, 60%of disc herniations are gone or smaller on follow up mri's 6 months later in people who get better-905 are treated non operatively.
Yes. It sure can. Just because the pain is gone does not mean the herniation is gone.
Yes. If you have a herniated disc, the MRI will show it. The majority of patients with herniated discs will get better in 6-10 weeks.