Hi! I'm trying to help with my experience of using camera LC5 and FL28
there are many possiblities and something may be damaged during your last shooting.
Carry out an inspection on the hotshoe connector (camera & flash)
I suspect that flash hotshoe connector (plastic part) already cracked
if no damage, then check on the camera hotshoe connector. Is any of the leaf spring (located at both side) missing?
Then you decide what to do next. send your camera or flash for servicing tomorrow. Request for a loan set from the service centre if it can't be repaired on the spot so that you don't miss your shooting in the evening.
That is all I can help you. I confirm that Panasonic service centre at Panasonic Building - 2 Jalan Kilang Barat (off Jalan Bukit Merah) and their business hours is as follows:
Mon to Fri: 8.45am to 5.00pm
Sat: 8.45am to 2.00 pm