Gallbladder symptoms with no stones

I am a 48 year old female and have been experiencing what I thought was gallbladder symptoms for a few weeks. They are bloating, cramping/pain in the upper right quadrant (near my right breast, under the rib cage, sometimes goes to my back and also has given me intense chest and shoulder pain), constipation, feeling of fullness, acidic feeling in throat/esophagus, feeling like food is crawling back up my throat. I would not describe the pain as unbearable, but a couple times, when the pain radiated to my chest and back, I literally thought I was having a heart attack. It is very similar to the pain I felt after I had my tubes tied and the anesthesia was wearing off, that pain you get in your chest and shoulders, and I'm told that was from gas. It does not hurt me to lie down and I am sleeping fine, but wake up exhausted! Bowels are extremely unpredictable, sometimes when I go they are thin and pale and sometimes they are large and very dark. I'm constipated and can usually only go to the bathroom with the aid of an herbal tincture that I got from my naturalist. My appetite is low and the discomfort is greater right after I eat. Just returned from the hospital where an U/S was done. Gallbladder is not enlarged and there are no stones. Can anyone help me?????