Running - after a while it hurts my groin (hip flexors?) what can I do?

[sassytheFIRST]

Been running 5k ish on treadmill for about 3 months. I've noticed that after half hour or so the bits of me where my inner thighs join my body get really sore -the same bits that stretch when you assume the smear test position . it's a muscular
pain rather than a stabbing one iykwim.

Is there a way I can build up these muscles?/Ligaments? It's the major thing stopping me progressing to running faster or further do us like to sort it if poss.

Pilates may help. But I'd be interested in anyone else more specific answers I have a weak left side one from post baby 1 six years ago and I have struggled to strengten it. But building core strength has helped.

Do you stretch before and after? I used to get that but mainly when I ran after a break or stepped up a distance. Stretching is helpful though, do you do any other activities that might work those particular muscles?

Also, see if you can find someone to look at/help improve your running form.