Hugs, Kit. There are some meditation apps you can use on your phone or, depending on how restrictive your internet is at work, videos on Youtube (though I guess you could also use those on your phone). I tend to do better with some sort of guided meditation than just sitting and trying to breathe in and out slowly, though that can help at times, too.

In terms of other things to calm you, I've heard splashing very cold water on your face can do something with the vagus nerve to calm you down. Or if you have a fan, blow some cool air on your face. For some reason, if I'm panicking, it also helps me to stand up (sometimes walking around, but just standing). I imagine it's hot where you are, from where you've said you live, but if by some chance it's not that bad out, stepping outside could help, too.