Your symptoms are likely due to;
1) Iliopsoas tendinitis
2) Groin injury
3) Pinched nerves in back; this is the most likely cause.
4) Hip tendonitis and bursitis.
The following may help you;
a) Physical therapy; exercise regime for back and hip.
b) Deep electrotherapy; therapeutic ultrasound and short wave diathermy.
d) Local analgesic cream
e) Pool therapy/hydrotherapy.
f) Analgesics like Nurofen/Ibuprofen
g) Lidocaine cream
i) Back brace.
You may start these exercises;
1) Straight leg raising: Lie on the bed with your back and remain in a relaxed position. Slowly raise one of your legs upward and keep it as straight as possible. Count up to ten, and slowly bring down the leg. Do the same with the other leg. Repeat this exercise ten times.
2) Curl-ups; lie on the back with knees bent, fold arms across the chest, tilt the pelvis to flatten the back, and curl-up lifting the head and shoulders from the bed/couch. Hold for ten seconds, then slowly lower to starting position. As strength builds, aim to complete one set of ten curls. The exercise should be done twice a day (both the sets).
This is a slide show for the exercises (you can pick up your own set, which suits you);