Diarrhea after Proheart and Protech injection

Has anyone's staffy ended up with a very upset belly and diarrhea after a yearly proheart and protech injection? My husband and I just came home to find our house covered in poo and wee (we had both our staffies inside in the aircon due to the 44 degree temperature today). He's been fine before with his yearly injections? My boy (Aussie) is 4 years old.
TIA

What possible side effects of ProHeart 6 should I look for in my dog?
• Severe allergic reactions (anaphylaxis): facial swelling, itching, difficulty breathing, collapse
• Lethargy (sluggishness), not eating or losing interest in food, any change in activity level
• Seizures
• Vomiting and/or diarrhea (with and without blood)
• Weight loss
• Pale gums, increased thirst or urination, weakness, bleeding, bruising
• Rare instances of death
•
If you notice any of these side effects or have any concerns about your dog, please contact your veterinarian as
soon as possible.

I'd contact your vet as soon as possible, please do let us know

Hope he's OK, let us know xx

Is there an alternative to these injections, maybe have a word with the vet about this too