Duty to Assist HLR say not service connected and service connected 5 months ago. Pre existed and aggravated now.

Hello

was service connected for a back condition in 2021  from  VA and HlR waited 5 months to get C&P on DTA and new Exam says not service connected and now they ordered an IMO and now they say it existed and was aggravated beyond its nature progression.  So,  no doctor visits in for a while and hlr asked imo are lay statements enough? Was treated in service and wonder if they are going to try to sever connection? Was DTA error and waiting for hlr to change to cue?  Whats your opinion?