Returning to swimming stagnant on speed

A few years back I was big into discussions on this forum.  Forum usage seems to have slowed down a lot but I'll give it a shot anyway.  I'm about 4 months back in the pool.  In 2015 I was holding sub 1:10's per 100 for a 60 minute timed swim.  From 2016-2019 I swam periodically with no focus.  From Dec 2019-April 2020 I had focus back and getting back down to that 1:10 per 100yd pace then COVID shut everything down.  4-5 months ago I started to put the time in again because I can't run anymore.  I am fricken' stuck!!  I am struggling to pace 1:15.  I can pace 1:17's for a 12x500 long set but if I do 10 x 100  on 1:30 I will die trying to stay below 1:15.  I have been struggling with this for about 8 weeks.  I did have covid back in dec 2020 and was pretty sick for a few weeks and then really struggled with cardio for months.  Now I have the awesome experience of a pretty serious anxiety attack during warmup if I start out too fast.  I am curious if anyone else has experienced this, not so much the anxiety but the major plateau.   I am swimming 3-4x a week, 3000-4500 on most day with a paced endurance day of 6500+ .  I am a life long endurance swimmer and love open water racing (not training).  I am a 46 yo male so I know age has it's hurdles but hell.... not this much right?  I am starting a new block of monday-Sat  as m-Swim, t-swim, w-lift, th-swim, fr-swim, s-lift.   

Is anyone else dealing with this? Any help would be appreciated.