i guess they may not cover, symptoms were there and it was known to the patient when insurance was bought.
but check with the agent and find out from the doctor whether the 2 things are connected
may be you should communicate with the agent (if there is) that helps you with the insurance first....it is important to show the two things are not related.
As long as MRI was done, there was a record of some sort of problems, regardless the original reason for seeking medical consultation. On top, the timing is so close and the insurance is so recent, the insurance company will be very careful for sure.
in any case, an experienced agent would be helpful, especially making sure the right wordings are used in the claim form and doctor's proof, and ensure the required documents are collected/submitted.
But after all, whether it is covered is a company policy.