Why is my "new" battery going dead after just 2 days.

I have owned this truck for 6 years and have had not issues. About 6 months ago I had a new battery installed and everything was fine. About 3 weeks ago the battery started going dead after just 2 days of no driving. I charge it up and drive it, then park it in the garage for a couple days and the battery is drained. I looked over the fuses and found a 30amp fuse blown under the hood. This fuse was the "batter saver/trailer tow" fuse. I replaced it but it didn't help the battery issue.

FYI: I starting pulling a boat trailer about 2 months ago and had a tail light on the trailer short out when putting the boat in the water. Still have the light plug hooked up to the truck. Would there be another fuse/relay that could be the issue?

Thanks!