Cominig UP (!) with something

[AnxietyLevelMax]

I am not British…I genuinely thought you say “coming up with something” as getting sick…have been saying it in the office forever, no one has ever corrected me. My husband (british) just told me it should be coming down! What an embarrassment! 😂 i even asked my colleague today if she is coming up with something as she was really cold..
not going back to work now 🥴

Guessing by your name you're overthinking this a little...

"Coming up with" something would be like you are developing an idea, or you're coming up with a plan, that sort of thing.

Don't worry about it, people obviously knew what you meant

YNBU, but did DH explain what "coming up" means?

Relax! Most people find those kind of little language misunderstandings endearing or amusing, in a nice way, not a mocking way.
If English is not your first language, you are doing very well.
I have been laughed at by waiters in Germany, trying to order meals and getting the grammar wrong, but they weren’t nasty about it and explained what I should have said. I didn’t lose sleep over it, and nor should you fret about your use of a different preposition. It’s not a criminal offence!

I wouldn't worry about it, my friend isn't British and sometimes says phrases slightly "wrong" but I know what she means.
I never think she's stupid or embarrassed herself. She can speak 2 languages! I can't!

You can speak at least two languages then? That's awesome! I'm trying to learn French, it's hard and I'd be scared of committing a linguistic faux pas (see, like a native).

I think most would have barely noticed, the rest would have thought it charming. A tiny minority would be sneery but they would be idiots and can be ignored.