Half marathon next weekend and the nerves are kicking in

I have trained and felt ok about the Hartford half marathon next week, then the final instruction email came and I became very nervous. Not sure why. The pre race nerves always make me doubt my training. Oh well. Last week I did 13.08 in prep in my area which is very hilly. I had a good run, did it in 2:05 which is great for me. This past week I have IT band pain and my planter fasciitis issues, but nothing too bad. Then today I went for a mileage taper run and had an awful run. I felt off at first and by mile 2.5 I started having stomach cramps followed by really bad cramps and nausea. Not good. I pushed through the 6 miles I planned on but had to stop and walk quite a few times. For a few minutes I actually thought I might have to call home for a ride, but decided I would beat myself up afterwards if I totally gave up. I am now hoping next week is a good run. I figure it must be better to have my bad run today versus next week, right? I am hoping for decent weather and a good pace and looking forward to seeing my husband PR on the full marathon.