2010 Toyota Corolla Rain damage I think

When it poured last friday really hard, I drove slow. There ended up being big big puddles in the middle of the road like it caused lakes to over flow. Which messed up the roads I drove a good 20 miles or less over each puddle there was about 2 and since than my car has been very loud when I turn it on than it gets quiet and than when I push on the gas it gets loud again. Friday night sounded like my whole bottom of my car was goin to fall off. Is this something serious. Ive gotten its my muffler its jsut wet let it dry out. Should I be concerned. This week it actually got a little quiet but its still loud. Please let know I dont have alot of experance with cars. And idk what to do. This is my only car and I dont make a million dollars. Any idea of the cause of this please let me know.