Are you sure it was a reaction to the booster? You took him out for a run straight away afterwards he could have reacted to something he rubbed against or he got stung? Not that I'm saying you should have your dog annually boostered, I don't actually agree with that, but I think a lot happened after the jab for it to be categorically the booster. If you'd taken him straight home and he reacted then yes I could see it was a direct link.
Becky

Bec the recommended vax period is now at least 3 years for vaxs other than lepto(which doesn't cover a full year nor any of the types of lepto found in the UK) so any vet doing annual full boosters is going against the regime advised by the vax companies

Yeah I thought of that and the vet said she couldnt rule it out, it could be a bee sting or reaction to a plant. She said though more than likely it would have been the jab. I suppose ill just have to keep a close eye on him incase it wasnt the jab. This was his first booster and he had no reaction to his initial vaccine, so I will be very careful in future about what we have done. I have wormer and flea treatment that I need to give him, how long should I wait before I do this? Its such a worry isnt it

I would wait at least a week free from symptoms before worming him then another week for the flea or vice versa!
Becky