9 YR old struggling with separation anxiety

[Daisydrum]

Hi, please if anyone has experienced separation anxiety (we think this has largely come about due to the pandemic) what would you suggest we do?
DS9 has always been happy and confident but there are times he will cry or begin to have a panic attack at the thought of going to an activity he enjoys because we won’t be there.
He has also started effectively telling me off if I am a minute or two late to pick up at school.
We are being supportive but do not want to say fine he doesn’t have to go as this will not help in the long run.
Any suggestions would be much appreciated

I’d acknowledge that it might feel scary but enforce that it’s something he can conquer and it’s not dangerous. Keep telling him that he is strong and capable even without you. And do your best not to let any of your own worries seep into his thoughts.
Don’t allow him to avoid situations which make him anxious - he may be left with a very limited world won’t learn how to move past his anxieties. Instead, help him build up a tolerance to being away from you. E.g, go to a play date together and sit in another room. The next time, leave for a short period of time. Then leave for longer stretches etc...

Thank you @Fivemoreminutes1 that’s really helpful

Helen Kennerley's "Overcoming Anxiety" might be worth a go.

Thank you I’ve just ordered it!

Is he being bullied by anyone?