I made a 3 tier wedding cake that I have made before. It was vanilla on all three tiers with bavarian cream filling on the top and bottom layers and strawberry filling in the middle. They were all covered with fondant and decorated with fresh flowers. The middle layer was horrible. It looked like it had a spare tire and the fondant was cracking on both sides when I put the cake together. The top and bottom were fine. I don't know what I did wrong. Please help, I don't want this to happen again.

Sounds like you overfilled the middle tier or your dam wasn't strong enough. I like to fill the cakes then let them rest for a while. I'm not a fondant expert so someone else may be able to help better with that part.