As a guy that runs a tire repair shop in saturdays to get some extra cash and considering you had that alarm for a while it means you have a small object inside the tyre. Not only it's not a major problem but it can get fixed in like 5-15 minutes tops.
You need to just stop at a gas station and ask the guy the put some more air in it as atm you are risking of wearing the tyre uneavenly. And then visit a tire repair shop ... dunno how much it costs where you live but it's dirt cheap in my country to fix something as minor. Like 2-3 Eu