Congestive heart failure is a very broad term for the heart not working properly. It is so hard to see our little guys not feeling well.
If he is throwing up yellow (bile) that is from lack of food in his stomach. I still think you need to take him in to see the vet but you can try feeding him little canned pumpkin with canned food or boiled chicken which help settle upset stomach.
Keep us posted on how he is doing.