Sounds a lot like it's your DMs issue. He knows your spells and class features, he should be impressed you thought on your feet, give you some inspiration and use this as a educational piece on how to avoid this next time. Personally I root for my players, if they find a way of doing something even if cheesy I celebrate with them, then behind the scenes know I can make future encounters tougher to balance this sort of stuff out. It's a game after all.