10 Yr Post Liver Transplant Issues Breathing

I am going to try and make this short but its hard.

11 yrs ago I noticed my hubby not breathing correctly. Dr said it was because he was a previous smoker. I kept insisting this was different. Fast forward his oxygen stats get way worse. Keep going to drs including a pulmonolgist who again says because he previously smoked.

Try a 2nd pulmonogist in our town. He finally figures out my husband has Hepatopulmonary syndrome and needs a new liver. Got the new liver and it totally cures him.

Now 10 years later he has trouble breathing again. Just like before which makes me panic a bit. Can this syndrome come back?? His surgeon for the transplant told me they "didn't think it could"

His liver numbers are off a bit but they always have been since the transplant.

He has an appt later in the week but I am just wondering if anyone has had the same thing