It could be a bursitis or a strained ligament. There are a lot of structures in there that can cause this kind of groin strain.
I'd assume you may have pulled something and it's recovering. I'd try loosening up the hip joint to see if that improves things / speeds up your recovery.
My favourite routine for that is to lie on my back, legs bent with feet on the floor. Grab one leg and shift it around in one direction a half dozen times, then the other direction. Repeat with the other leg. [I find this lengthens my stride so I can walk faster.] Might do nothing for you but I think it's something harmless to try.