No known software changes prior to the problem - correct?
Have you tried (if available) another USB port on "my computer"? Intermittment connectivity suggests a hardware problem. USB ports can be problematic.
And, even though the existing USB wireless adapter works well on the the other computer, I would still try another USB wireless adapter on the computer/location in question. Just to be sure that the current USB wireless adapter is not the culprit. Hopefully you can borrow another adapter from someone.
When you tried the USB wifi network adapter on "my other computer" did you move that computer (if possible) to the exact location of the "my computer" per your first sentence? Maybe there is now some new local environmental factor disrupting connectivity that was not present in the past. E.g., any remodeling, wiring changes, router moves, and so forth prior to the problems you described?