Non-Verbal 2 year old....having a hard time with tantrums!

I don't know if there is anyone else out there facing this, but I hope to find a least someone who can help. I have a completely non-verbal 2 year old boy. His hearing is fine and he follows directions, can point to objects if you ask him, etc. He makes car noises, dog noises, cat noises....but no words. He was starting to speak some when his sister was born (he was 20 months old), but since her birth, he has stopped words completely. He just points and uses gestures to tell what he wants. He also used to be very well behaved in public places, but we have had to stop going to church completely due to the tantrums every Sunday. When he throws tantrums, he screams, throws objects, pulls hair (mine, his sisters), bites the dog, and throws himself on the ground violently. We have tried every way in the world to avoid the tantrum, but they occur when we don't understand what he wants. He can't tell us what he wants, so therefore we are guessing gestures....too many wrong guesses and it's a knock out drag out. It's extremely embarrassing to take him in public anymore, so we just stay home. We bought a broom at Wal-Mart once, and it started a tantrum because we wouldn't let him hold the broom and sweep Wal-Mart's floors. We literally drug this kid out of the store screaming and kicking....over a broom. Please....someone offer me some advice. I can't take it anymore.