I have had an on-off groin injury for ten years now, at first the pain wasn't too bad, but after a year I took part in a half marathon and I couldn't walk for a few days after so I got it checked out.
After numerous scans and tests, they advised that due to it being left so long mine was chronic as well.
I was put under aesthetic and given a cortisone injection, and after the recovery period it did feel a lot better, but it was never back to normal. They advised this would only last a few years (and that you are only allowed 2-3 maximum in one area in your lifetime).
I was told I could never run on pavement again, as the impact is too harsh, and to continually do the exercises given to me by my physiotherapist.

I gave it a year, focused on weights and soft running (on grass or the treadmill) and decided to start running on pavement again.
I ran for only about 10 minutes, and the next day the pain was back. Luckily with a few days rest it was ok again, but shows that it really isn't practical to run on pavement.
The pain has now started again, and I haven’t even run recently, so looks like I will be having another injection (last one was 4 years ago).

I hope yours isn’t as bad as mine, as for a keen runner, its pretty dampening news.
Things that do help are continuingly doing the exercises given to you, doing yoga regularly and running in water.

Hope the info helps