Pain in body. I consulted many doctors!

I am a 25 year old male weight 63kg have back pain problem. In my back I always have pain in muscles ( I think). It's all over back ie in hip joints, shoulder blades, neck, waist etc. I feel my muscles are weak or I have a week body. Sad. I never feel free from all pain , streets, stiffness. Also my body movement is low. I am unable to bend my neck in all directions. I feel pain when somebody push me from back suddenly with a force or sudden movement ( sometimes while sneezing). I am not able to lift heavy weight. I feel tired after some work. I consulted many doctors regarding this but no one able to find root of this problem. All test negative. So what to do. Which type of specialist doctor do I need to consult for this problem. Please help. Q1 :- I also have GERD but now I am taking medicines for it after consulting gastroenterologist. So is GERD is the root cause. Q2 :- Is it possible that this came from hereditary. My dad had joints pain problem.