Biting

My son is 20 months old and is having a serious biting problem going on. He has been in daycare since a baby. He loves the school. Right around 16 months he started biting at school of course he learned it cause some kid bit him. Well the last 3 weeks were rally bad he bit 3 kids in 4 Days and next week he was fine than last week he did it agin 3 bites in 4 days and then shoved a kid. They kicked him out of daycare. I was devastated. He is s good kid but he does have a temper. When he gets mad he bites or hits. I am super concerned about him starting a new school. I am not sure why he does this. His teachers say he gets super frustrated cause he cantexpress his emotions.l don’t even know what to do. Some say it’s toddler behavior and some say he has an miss directed anger problem and I better get him in control. I feel helpless. Any other mamas having this problem? How do you get him to stop biting!