My little dog Chester has been on Vetmedin for over a year for a heart condition and has been doing great. He had diarrhea and vomiting this morning (must have eaten something he shouldn't, he's a sneaky pup). He's done with that, but is extremely lethargic. Drinking water, but won't eat. Doctor gave me Metronidazole 2 years ago for a tummy bout. Does anyone know if there are any contraindications between those 2 meds?