Here you are talking some thing about stone its not clear. Is it some thing you are taking about
kidney stone? As well there is no idea about your age, over all weight, how much it was ? and how much it is now? You need to provide your details properly. I will give here generalize answer since many things are not clear.
For burning sensation in stomach, it can be acidity problem also, as well it can be gastric ulcer also, here you need to consult a doctor for evaluation and treatment. As well need to change your food habits. Keep snacks minimum, have more of cut fruits in diet. And keep one time for your food intake. Break fast keep it good, lunch keep it average and dinner keep it early by 8:00pm or before and keep it minimum.
Next for your
chest pain again it can also be related to gastric issue in your case. Since you are not more in weight and loosing weight I am not suspecting any thing with heart. But do consult a doctor if you start getting breathlessness along with chest pain.
For your
back pain if its only at back then it could be related to spinal
muscle weakness or over use soreness. Here you need to check on your working posture as well sleeping posture and the bed also should be suitable for spine. Detail guidelines you will get from physiotherapist. You need to visit physiotherapist and based on your back pain assessment they will suggest you exercise program which you should follow up. This will improve strength and stamina of spinal muscles.
As well physio will only advise on ergonomic too and you should follow with that too.
Any time if you have
radiating pain from back to legs with
numbness do consult orthopedic too and go for needed test.
Also you can use hot and
cold pack on your back for some more pain relief by relaxing and having soothing effect on soft tissues.
Take care.