I understand now.

YouTube - Revolution of Kicking - Side Kick

You can see anantomy of a side kick in this video, mostly from 01:00 to 01:40
Pain comes when I extend my leg and also a silent click. I can feel the pain only in hip joint, nowhere else in my leg.

Another kick that is causing pain in left hip joint is the middle section front kick (between waist and chest). I can hear quite loud click in my left hip joint when performing this kick but, only if doing it slowly.
ist2_1038357_karate_front_kick_mae_geri.jpg < this is the front kick


Ask for more info if you wish. Thank you
Kihap