I'm surprised it worked at all. The ladder you mounted it on may indeed be DC grounded. However, vertical antennas require a groundplane which is essentially the "other" half of the antenna. Quite obviously, the ladder is a poor groundplane. The original SWR was low for two reasons. One, the antenna is rather lossy, and two the lack of a good groundplane.
Now that the SWR is too high and can't be brought down to an acceptable level indicates another problem altogether. I suspect that one of more connectors loose or have water in them. Perhaps even the antenna has water in it.
The first thing to do is replace the antenna with a dummy load and recheck the SWR. If it isn't okay, you have a problem with the coax. If it is okay, then start looking at the antenna. Whether or not it is DC grounded makes little difference in this case.