I Went Through Angioplasty 5 Months Ago. Took 4 Weeks

I went through angioplasty 5 months ago. Took 4 weeks rest and then resumed work. Have been maintaining a discipline of walking for an hour 4 times a week and very basic work-out at the gym for 10-15mins. Have been doing medical check-ups regularly and the blood test, ecg and echo and stress test have been normal. Had a test done 3 weeks back and the report was normal.
Yesterday, evening when I went for my walk, felt heaviness in the chest and I immediately stopped and came back. Took rest and was fine. I have been burping since evening. Please suggest.