胃痛一個月

You should do some blood test for the level of Helicobacter 幽門螺旋菌, because if the level is getting high than normal then you need to take medication for 5-10 days in order to clean, otherwise, your stomach will keep on uncomfort.
Black faeces means there is internal bleeding, except if you ate something in black colour food.
Worried always make stomach get more tense and stress, it also create discomfort, to ease your mind, you better have blood test done. Take care and be more careful to choose your diet.

i think you have to trust the test result but i suggest u to get second advice from another doctor (or another hospital) to make sure the medicines are good for you; i wonder the dark color is just temperary, will it be too young for you to have 胃酸倒流? ? Ether you are very fat or you work( study) under very high pressure, sometimes people feel physical pain when they are streesed or nervious...
But, u must take good care on your diet from now on to stabilize your sickness, obviously you have problem of digesting, so eat more liquid things like congee and veg. soup., try eat more banana can improve somehow.
中大消化疾病研究所在1996至2002年，監察32,807名在威爾斯親王醫院接受胃鏡檢查的病人，發現胃酸倒流發病率，由96年每1萬人有2.3人，升至02年每1萬人有5.8人，7年間增幅逾1.5倍，當中兩成患者屬40歲以下。至於食道炎病發率亦由每1萬人有0.8人增至1.9人，去年更增至2.5人。
6％同時患嚴重食道炎
中大醫學院消化疾病研究所主任沈祖堯教授表示，反芻的胃酸會灼傷食道，引致食道炎，甚至食道癌。
研究中，40歲以下的胃酸反流患者，6％同時患上嚴重食道炎，而外國亦有研究指，嚴重胃酸倒流患者患上食道癌風險是一般人的44倍。他預計未來20年，胃酸倒流引致的癌症個案會增加。