Yes, you have it the right way round.
I personally used to have frequent bouts of pericarditits (fingers crossed not since my heart surgery, as they cut part of my pericardium away). The pericardium is the sac that surrounds the heart muscle. It can become inflamed or have an infection in severe cases. I personally did not have any water retention or swelling in my feet and legs because of this. As this was the sac and not actually the heart muscle I can't comment on what affect endocarditis would have on swelling and water retention.
I'm not medically trained, but I too think your husband needs to go to his doctor. Might I also suggest that perhaps he asks if it would be advisable to go on a low dosage of diuretics. They hopefully would then stop fluid build up in his system. Just an idea.
Hope things improve for your husband and yourself soon.