4 year old behavior HELP

Ever since my 4 year old has started Pre K we have noticed a HUGE behavior change. He’s aggressive, doesn’t listen and throws everything and he used to not be like this. It’s to the point where I’m concerned and I don’t know what do. Before he started pre k at a public school he was at a center daycare so I wouldn’t think the adjustment would be this bad. I don’t know how to handle his meltdowns anymore. I feel terrible but it’s like I hardly even want to be around him anymore it’s so mentally draining 😭. Any advise would be greatly appreciated!