Your form sucks. Sorry, has to be said. You get strong from doing proper deadlifts and squats. The only time it hurts is when I do it wrong.
Keep reps low. 3-5. Do supporting work (Hypers, crunches, etc) in the higher range (10-12). Stretch.
Check your hip mobility.
And also, you have been hurting for two years and decided all of a sudden "Hey, I'll post here?". Go see a professional. Chiro/ART, doctor, etc.