I am sorry to hear about Frankie.
My name is Rebecca. I am a veterinarian, and will do my best to help.
Is he taking any medication for his heart problem?
For diarrhea, you can try over the counter medication like Loperamide ( one brand name is Imodium).
How much does he weigh?
I am not seeing responses from you. I can try to connect with you another way.