NO!! Your CORE is not weak!!
Example 1 : Pain in the back
Many suffer from back pain and only few get the right advice.
One general advice is your core is weak, it needs strengthening.
Body cores are not necessarily weak , we believe in evolution and accept that it was smart enough to give us a brain but not smart enough to make our cores strong enough or biologists incorrectly termed the trunk as the core of the body or the english language wanted the word core to mean peripheral and not central.
If sitting damages cores then i should not be seeing rickshaws and taxis being driven around.
Core strengthening may help compensate or does help you to get to a point to be able to address the actual issues
There is more to the back than just the core. Posture, movement, daily activity all matter.
The strongest core wont guarantee absence of discomfort while the weakest core can show no discomfort at all.
Your Core is weak is the first line of defence when ppl who have got nothing to do with your suffering say things like shaadi ke baad sab theek ho jaayega especially when kids disapprove of family choices.
Today many doctors are against invasive procedures of any kind to bones and joints unless absolutely required, so consult them over google.
Google can connect you to some good therapists or help diagnose the issue but seldom help you treat it !!