Cure itself by tomorrow? No, unlikely (I think you probably already realise this ,,,). Can you get it checked out soon (i.e. before you run again) so that you know what you're dealing with and whether or not you can risk running on it??
At the moment you don't/can't know for certain what impact it'll have on your marathon ... you talk about screwing up so close to the end, but you really will make your race an impossibility if you just keep on running on it, HOPING it'll be OK, when you don't know what the problem or remedy is. You MIGHT be able to not run between now and the marathon and still be able to get around the marathon one way or another (you would need to revise your expectations); whereas if you run again too soon and it finishes you off completely then you won't be able to do the marathon at all, even slowly. Is this what you want ... to feel that you've followed all the training plan to the letter but are unable to run the race, or to forget about the training plan for a bit and still have a shot at the race?!
Sorry to sound negative but I've recently seen someone with similar circumstances and I can't see the sense in risking months of preparation now at this stage, just for the sake of accepting that you need a bit of recovery time and being prepared to adjust your race goal ... gather more information (from someone who knows what they're talking about!), THEN decide how to proceed. Why would you risk aggravating it further in the meantime?
Best of luck ...and please post an update as and when you have one!
OP, best of luck with your new regime! Don't let anyone put you off I've been negotiating with myself all day about whether or not to go for a run (it's sooo cold!!) and it's taken your post to remind me that if a beginner & a 12y/o can resolve to religiously follow a plan and inspire others then surely I can drag myself out for a short gentle jog too! Look forward to hearing how your session today goes!