Hello welcome to health care magic. I have gone through your question very diligently and I really appreciate your concern. Looking at your description, I would advise you for a battery of tests like blood for hemoglobin, CBC, liver function test, blood sugar fasting and post prandial, Urine test for routine and microscopy or an ultrasound if need be Here I would like further information like if possible upload me all your previous report, are you diabetic? so that I will be able to guide you better. Back pain with dark color urine and increased frequency of urination in back drop of history bof renal stone, chances of urinary tract infection or recurrent kidney stone are more likely. For gas in intestine, I would advise you to take antiacidity medicine like pantoprazole or ranitidine group of drugs with antacids, have lots of fresh fruits and vegetables you should drink plenty of fluids either water of fruits juices to maintain good hydration and urine output which will help by flushing out the infection. Hope this answers your question, please feel free to ask for follow up question, I will gladly answer you. Best wishes