have you changed your running style to compensate for other problems?
Small changes can have large effects.
So did mine,
very much like they did 5 summers ago at the Ballater Games (Aug 8th 2013) and a month later on AS and a month after that at the Skyline. (each time a different group of thigh muscle seized)
IOMS (Instant OMS)
Today I walked about 100 yards (vertically) up the Chapelgill race route. as soon as I turned round muscles seized - maybe more ITB than quads. Eased through the evening .
I wondered then if I was carrying a virus.
THis time I'm in the midst of the "flu" which has been going on for weeks.
IOMS sums it up perfectly. Two days on and still a bit sore, no other symptoms. Running style is all over the place at the moment, so could be a factor. Thanks for the advice.