Unknown problem. Continues generation?

My dad sometimes find difficult to stand on feet or walk. He walk like old man and says stifness in stomach pain near lower back sometimes upper back not at fixed place. Sometimes he is ok all normal and walks properly. As he stands up he burps too much and find easier to walk. He states this problem triggered after it was not immediate, he was picking up bullet bike and when returned home this symptoms shows. He visited hospital did test diagnosed with mild ulcers in esophagus. Diabetes is normal under control. Even after taking medicines for more than month this problem continues. Unable to understand problem. But there is too much burps. He wakes in night sit and burps continuously and find difficulty in getting continue sleep. Sometimes its normal. He stopped eating dairy and rice. One day he ate rice and milk problem worsen. Is this problem related to gas or nerves due to accident on bike? Is gas trapped in his body but unable to release it properly? Is there continues generation?