I had the exact same thing happen. I took it to the professionals and they repaired it. I think it last a month or 2 and then it blew again. It was a complete waste of money. Since we had to pull the tank to do the repair, it would not have cost much more to pull the tank and put in a new than it did to pull the tank, repair and re-install.
I would recommend that you simply bite the bullet and put in a new tank. I left my repaired/leaky tank in there and by the time I could replace the tank I also had to replace the floor and that makes for an even bigger job. I ended up doing it all myself saving hundreds of dollars but it took a lot of time and since I also had to remove the black and grey tanks during this operation there were things I would rather not talk about that needed to occur while these repairs were being done.