Don Omar Postpones 3 Shows After Respiratory Infection Relapse

Don Omar's been having a rough go of it lately ... a resurfaced illness has forced him to postpone the 3 concerts he'd already rescheduled.

The singer announced Tuesday that he had to postpone his Ontario, CA show that had been rescheduled for that night ... and it wasn't much longer before he announced he had to push back his Vegas and Salt Lake City stops, too.

Don explained he relapsed from the respiratory infection that had just benched him not even two weeks ago.

He took to social media to issue a lengthy apology to fans, even sharing a shot of himself at the doctor's office.

Don said he's devastated to pull out of the performances, noting these ticket holders already had to shuffle around all their plans ... and he hates the idea of asking them to do it all over again.

He thought he was doing better after hitting the stage in Cali over the weekend ... but his doctor has since ordered him to stop and rest.