Sir this like inflammation of the joint between the lower back and hip. Maintain good posture and whenever you lie down straight , place a pillow under your knee.

Ensure that you maintain an appropriate posture while working or sitting or walking....Take frequent stretch breaks and drink lots of water...Discontinue using pillow while sleeping straight...Do not lift heavy objects, especially after bending down....Eat a healthy wholesome meal which should satisfy your minerals and proteins requirement...take over the counter pain medications.. Consult nearest orthopedic surgeon they will do the needful.

It is sciatica. Start with back pain relieving . Sending you the android  link of the same https://play.google.com/store/apps/details?id=com.backpainrelieving.backpain