I've got one of those at the moment and they usually take 2-3 weeks to recover from.You need to rest it fully or you risk aggrevating it and that will cause problems in the marathon. You will only lose one week of training that would have counted / helped you in the marathon. One week is nothing, your training has affectively been done. Dont worry either....sometimes less is more.
Well my intended LSR of 14M turned out to be only 12M and mile 9 was very difficult. I’ve had two LSR’s like that now and I think that my body is telling me that I haven’t really got the foundation to do the marathon training.(There have been other factors too but in the main it’s the lack of miles). It shouldn’t really be a surprise to me considering my inactivity over the last couple of years. But I still think I have done well to get where I am it a short period of time. With only 5 weeks before tapering starts, if I carried on, I’m only going to manage to get up to 17/18M and even that will be at a push. So I think the wise decision will be to postpone until next year but carry on with my training in the same way. Not the same motivation but I’ve got a couple of HM lined up so something to aim for.