This sounds like an (bad) instant replay of my story in 2012. I had metallosis, 2 revisions (both sides), massive cleanup of bad tissue, and then a dislocation. The surgeon explained that in the revision, they leave the cup in the acetabulum (pelvis) and put in a new non-metal liner. Then remove the metal head and replace it with either ceramic or titanium. Sometimes, if the original implants weren't perfectly aligned, they can't get a really good fit and have to go back in and use different parts or position them differently. After they did that for me, I have been fine.

It is possible that if your metallosis was severe, that your body is still dealing with getting rid of the metal ions in your blood. If there is still microscopic metal in your tissues, it will eventually be absorbed. If there are visible shavings, there will be more cleaning up to do during the revision. As far as I know, removal and time are the treatments for metallosis - there is no pill or therapy to do it.

You need to be your own advocate here and ask some hard questions. When you go in for your followup appointment after the MRI, do you have a friend or family member who can go with you and take thorough notes?
First, how familiar is your surgeon with complex revisions and metallosis? Not all are, and a good one will admit that.
Second, what is the exact revision plan? Not just "in general" but what do they see, and what do they plan as a remedy?
Third, if this is not their area of expertise, can they refer you to someone local who has more experience? Or a teaching hospital or university with a great ortho surgery department?

I'll be waiting to hear how things go for you. For now, you may need to focus on writing down all the questions that you want answered.
Sue