Sorry, things didn't go as well as they could have done on Sunday, but you have had quite a year already with family issues. You mentioned stomach problems, and my advice will sound a bit industrial but try and go to the loo/ number 2's for as many times as you can. I hit a pre-race PB of 5 on Sunday, its normally 4, but I find it really helps when you then take on gels/ drinks/ anything.
Recover well and run a great one in Yeovil. Your London run will give you great performance boost for that.