What Causes Pain In Lower Abdomen And Upper Chest?

Hello, I have been to a doctor but still don t know what s wrong. I experience pain in my stomach and intestines, lower abdomen and back after eating as well as chest pains periodically throughout the day. I often feel week or tired and recently have had pains in my spine that make it hard to walk or bend (upper and lower spine). It usually is uncomfortable when I urinate but the doctor says there is no sign of infection in my bladder ( I constantly have to go through out the day and at night a few times and hardly any urine comes out and there is a slight burning sensation). Any ideas?