I would strongly agree that if anyone ever sees any kind of unexpected reaction to a vaccine, get an emergency vet on the phone if it is out of hours. Reactions can very quickly become fatal in the small number of dogs that do have a reaction. One reason why it is generally better to have a vet do a vaccine than to self administer is that if there is a reaction -- and severe reactions tend to happen very quickly -- the dog will have a good chance of surviving. It is generally considered a quite serious issue and so getting vet advice is really, really important if anyone sees a significant reaction/change in behaviour once their dog is back home.
I know people often come here for advice before ringing a vet or acting to get a dog to a vet, but I really want to stress again that none of us here is a vet or can diagnose from a board post, and there's no guarantee that the advice given is the right advice.
In general, when there's odd behaviour, distress, significant illness -- it is just so critical, and may be the difference between a living or a dead cavalier! -- to get professional advice.
Vet offices generally will tell you right away if the dog needs to come in and if there is anything you can do to give emergency treatment that may help relieve distress or even save the dog's life. All of us should choose a vet where we have the relationship that enables us to call them and get good advice.
I would also only ever use a vet that has an out of hours emergency service as well. I have needed to use this twice -- for phone advice -- and it was very reassuring to get pro care on what signs to watch for that would signal I needed to get my dog into the vet office.
In future, I def would not give two vaccines plus Frontline at the same time -- that is a really hard hit on the immune system, and you are right to wonder why vets do this
. If lepto and Lyme are considered critical for your area, I'd do them two-three weeks apart and wouldn't ever Frontline at the same time. I think Lyme is quite controversial as a vaccine? Might be worth researching whether it is actually needed.