It very much sounds like you’re suffering from some kind of arthritis (most likely gout).
But you don’t want this misery to drive you to neglect a different problem (having more than one health crisis at a time is a thing). Annoying infections getting around at work is also a thing that happens obviously. If you were having a drug reaction, it’d get stranger and worse over time and I very much doubt it’d hit you after you’ve been standing or walking for too long.
In case there was a misunderstanding, you can get constant low-level inflammation plus regular flares without medication. It can basically turn you into an invalid. Medication could trigger it I guess but if you’re prone to this type of gout, not taking medication would in time have gotten you to the same place.
I should also add that I don’t recognize the exact symptoms you’re describing but that’s not surprising.