[Ellie May]

I'm very sorry.

Trifexis and Comfortis are highly questionable (jmho). They are newer and already have a ton of reported side effects. I personally wouldn't touch either for my dogs (nor would my vet for her dogs).

If the goal when giving Trifexis was to avoid the Comfortis reaction I'm not sure what your vet was doing...

I'd go to Heartgard and see what you get (Program for fleas). Heartgard Plus is fine. They may still make the regular Heartgard which would have less chemicals.