Your pain needs further evaluation by a physiotherapist .Practising breathing exercises and specific exercises for muscular pain relief under physiotherapist's supervision can help in a great way .

This could be a result of awkward sitting habit at your workplace or there may be strain due to twisting, improperly lifting some objects or over stressing a muscle beyond the limited ROM

Do  deep breathing exercise and avoid gastric issue.

Chiropractic Mobilization will help. Bhujang Asana – Lie flat on your stomach, keeping the palms out, bend the neck backward, take a deep breath and while holding it for 6 seconds, raise the chest up. Release breath and relax your body. Repeat the exercise 15 times twice daily.

Being a government employee you must be sitting a lot. The awkward sitting habits has lead to muscles stiffness in that area which is giving you pain.

Left side chest pain. U must mention what type of pain, and wheather it is constant or fluctuates with activities or position like sitting, lying or during sleep. *If all cardiac and gastric test are normal, It can be due to neck (cervical spine) problem or pathology. And the pain readiating to chest or thorax area.

As you have done all the tests and there is no systemic problem, your pain could be due to muscle spasm or strain. Do you have any previous history of neck pain or back pain? Do you have radiating pain? Do you have pain on your left upper back (scapular region)? Did you start any exercise or weight lifting in recent past? We need some more details for assessment.

Pls check ur  Vitamin D levels.. Also start doing few breathing exs  n some scapula ex's..

There can be different reasons of pain need proper assessment. It can be due to postural issue also. Try to visit to nearest physiotherapy clinic to find out the cause of pain . And if it is muscle spasm or muscle sprain it can be corrected with exercises. So need proper diagnosis of your problem so better treatment can be advised.

There are a few possibilities apart from pain originating from organs. - There is a condition called cervical angina, which is the neck referring a chest pain. This needs neck mobilization and exercises. - There can be referred pain from your thoracic spine.  Thus also could do well with mobilization and exercises. However the heart, lungs and other organs need to be rules out before looking at these possibilities.