Fatigue after surgery

I had bypass surgery  to repair a problem I had I was born with. It's been over 3 years and I still don't fill back to normal. I stay tired and ache just about all the time. My doctors tell me my heart is in very good shape. I
do take medicine for high blood pressure and cholesterol. My doctor has tried different meds to try to help the achiness. It seems like things get better a few days and then the achiness returns. I do push myself to exercise and might go 3 or 4 days in a row.  I'll start to think i'm getting better and then I'll hit wall and it's all I can do to get out bed in the morning. When I get home from work I'm so exhausted I have to stay in the bed til the next morning. This might go on for 2 or 3 days before I get any energy back.  On my very best days I only have about 75% of the energy I had before surgery. Most of the time it's more like 50% or less. Has anybody gone through these symptoms for this long after surgery?