Greetings, sorry about the pain.
You have got flexibility issue with your back, desk job actually makes you less flexible at back and leg. do hamstring stretch, see YouTube for video of it. Pain goes down by 50%.
Next Steps
consult with physiotherapy who is well versed in trigger point therapy and posture correct, your problem will be solved in 2 weeks. continue exercise as advised by physiotherapy for 3 months to see full benefits.
Health Tips
vitamin d supplement is essential to build muscle and bone, take them as advised. if any concerns do let me know.