Jodeci lead singer K-Ci had to take a time-out because of a serious health scare -- after going down with a bout of pneumonia!!!

We're hearing he's alright, but Jodeci is canceling this weekend's tour dates as a precaution.

K-Ci's manager Michael Paran tells TMZ, K-Ci was hospitalized for pneumonia and has since been released and is at home resting with antibiotics. Phew!

Michael says this weekend’s concerts have been canceled, but hold tight "Freek'n You" fans ... they're working on rescheduling the shows for later dates.

All upcoming Jodeci shows after this weekend will proceed normally, as the group expects K-Ci to make a full recovery with rest and care.

The legendary R&B group was slated for a Valentine's Day romp in Brooklyn at Kings Theatre and a follow-up show in CT over the weekend -- but K-Ci's well-being is now the TOP priority.