Odds are high that your antenna mount is the problem. If you can take a good sharp well lighted closeup photo of the mount from the top and bottom, that will help so I can give you some specific advice.
More often than not with such a high SWR, the antenna is shorted to ground from the plastic insulating washer being missing, mounted in the wrong location, or broken which allows the antenna to touch the mount which shorts it to ground.
Is your mount like this one? If so, look where the insulated shoulder washer is and make sure yours is identical so far as where the illustration shows it to be located.
Only the bottom of the antenna mount, shown below the mounting bracket, should be grounded. Nothing above the mounting bracket should be grounded or showing a connection to ground.