Front hip = hip flexor. Groin is inside of leg. Which one is it
You can do reverse warrior lunges. But take it slowly, especially if it hurts. one leg back, rotate oposite site, squeeze glute of back leg. Take it slowly, don't force it. 3 x 8, alternating legs (one rep left, one rep right). Picture:
Second thing is trigger point therapy. Grab a little ball, and do what is described at end of this video:
www.youtube.com/watch . That one is for the psoas, aim for the hip flexor, which is lower (check on a map). You'll probably feel pain there when resting on the tennis ball (but when you try the other leg you'll hardly feel anything).
Good idea to do glute activatione exercises (birddogs, supine bridges etc) in the meanwhile.
Let me know how that goes. Doctor diagnose always help knowing what you have exactly of course.