Side lunge strength work injury

This has happened twice:

side lunges holding 2x 2kg weights.
As I step left I had a sharp pull on the right side of my lower abdomen, pain shot across to the left of my lower abdomen. It has settled there as a low level pain. The second time (2 weeks apart) I had the memory of the same pain as i stopped myself falling of my mtb going over slippery roots - I put my left foot down.
There’s obviously a weakness there. i had a full abdominal hysterectomy 13 months ago. I do regular strength work.
I would be grateful for any ideas on what to do to strengthen this particular area.