I'm sure you would agree that your doctor would be the best source for advice on this. But I think the walker/seat combo might not be a bad idea, especially if you are travelling alone. Coral Princess is a very long ship; there is always a place to sit close by in the public areas, but the hallways on the cabin decks are quite long with only three foyers in almost 1000 ft..
And some of the walkways on the upper decks have long distances between places to sit.
Hopefully you will be past this episode before your cruise. But if there is a chance of a recurrence I think you should consider the walker.
Please keep in touch and let us know how you like Coral Princess.