What should I do?

I'm due to run in the Brighton Marathon next weekend and am looking for some guidance / advice for a possible injury.  I've run 4 marathons previously and am looking to run a London GFA time (sub 3:10).

I've had some shin problems in the past, due to that and quite a busy work schedule, my training has pretty much been 3 runs a week - Tuesday, Thursday, Sunday.  This has all worked quite well and I've been feeling quite confident of hitting my goal time - I've run 22 miles on 5 separate occasions and have on the whole not suffered any ill effects.

However, last Tuesday (26/3) towards the end of my run I had a pain on the outside of my left ankle.  I didn't think much of it as I hadn't had anything like it in the past and it felt as much like I'd suffered a kick on the ankle as much as anything else.  As I still felt a bit tender on Thursday I did the sensible thing and didn't run.

Things felt OK on Sunday, so I went for my long run (22 miles).  I felt the ankle was a bit sore after 8 miles, but nothing genuinely painful, such that I'd easily forget about it for long periods of time, so I carried on.

On the whole, I didn't feel too bad after the run on Sunday, albeit again there was some tenderness around the ankle and achilles area.  Therefore rather than run on Tuesday I went for a long bike ride. 

However, I've just been out for a run as things had felt ok, but I stopped at around 6 miles as I was beginning to get quite sharp pains through my achilles and my calf.  I think I did the right thing as although I could probably have continued it was getting sore.  It doesn't feel too bad right now and I can walk around on it ok.

So, what should be my plan between now and Brighton?

Should I just refrain from running until the marathon in the hope that it gives it the best possible chance of recovery?

Should I have a run on Sunday to see how it is?

Any general advice / rehabilitation suggestions will be greatly received.

Thanks!