Near miss or possible catastrophic failure?

Had the most terrifying experience on a Malaysian Airways internal flight from Johore Bahru to Kuala Lumpur tonight. The plane was a Boeing 737 and was a very old and tired example of it’s genre with the interior very worn and dated.

We were turning to the right quite heavily during the descent into KLIA when the plane suddently lost altitude followed by a very loud bang. The plane then tilted violently the other way to the left as if the pilot had overcompensated in trying to get the plane level from banking to the right and I swear to god I thought he’d lost control and we were going down. I honestly thought we’d hit another plane and we were damaged but thinking about it now the sound was more like a hydraulic ram slamming. But anyway it was truly terrifying we seemed to fly directly and quickly down to the airport from that moment culminating in an eventual very heavy landing on the runway.

The captain came on the intercom as we taxied to the terminal and said that the “incident we had experienced’ was due to the pilot having to take an “immediate 30 degree turn” to avoid another aircraft.

I have my doubts about his explanation as I think the plane was completely clapped out and some sort of mechanical malfunction happened which the pilots were (just) able to recover form and it simply didn’t feel as if we’d suddenly turned to avoid another aircraft. So could any of the pilots on here give some feedback and advice as to whether or not they feel we just had a near-miss or perhaps luckily escaped a catastrophic failure?