Good morning @jelilien. Myelodysplastic syndromes (MDS) are a group of disorders caused by blood cells that are poorly formed or don’t work properly do to something amiss in the bone marrow where all the blood products are produced.
In your dad’s case it’s his red blood cells which are not reaching full or healthy capacity causing anemia. When that happens, there is a serious lack of oxygen being supplied to his body/heart/lungs which can cause the extreme fatigue he’s experiencing. It can also force the heart to pump harder causing that muscle to enlarge. He also has a partially collapsed lung which is adding to the heart working overtime.
He’s being treated with epoetin/epogen/procrit/retracrit, all of which are medications used to encourage red cell production. Reading the side effects of these meds didn’t show any specific symptoms that correlate with what your dad is experiencing. From my experience with having leukemia, the disease itself is most likely causing your dad’s symptoms.

When someone is admitted to the ER the medical staff will focus only on the immediate concern for the visit. So they won’t generally go into the details of other findings. That would be for your dad’s doctor with a followup visit.
Does he have a followup? Is he doing any lung exercises to help heal his partial collapsed lung?

Posted below are a few informational sites on MDS to give you a little insight to the Blood condition and possible treatments.
https://www.mayoclinic.org/diseases-conditions/myelodysplastic-syndrome/symptoms-causes/syc-20366977
https://www.cancer.org/cancer/types/myelodysplastic-syndrome/treating/general-approach.html
https://www.mds-foundation.org/what-is-mds/
~~
There are a number of conversations in the Blood Cancer support group. This one is about MDS with members discussion potential ways to increase red blood counts.
https://connect.mayoclinic.org/discussion/mds/
With members @jaylevel1 @littlelindysue @loula @tyson1221 @teteryan1 @shels93 @marcyjo

You can also type in MDS in the top search bar which will give you a list of all the discussions.

Is your dad working with a hematologist? Right now it looks as though they’re taking the route to increase his red blood cells. Have they started him on any of the treatments for MDS?