Can someone please help me w/ experience in digestive disorders, or gallbladder problems?

I am trying not to stress myself out about this but it's starting to worry me. To start off with I am a 25 yr. old woman in good health or at least I think I am. I am 5 ft. tall, 117 lbs., with good blood pressure (104/68), and I try to exercise and take care of myself. I had my gall bladder removed in the middle of Oct. so I've had it out a little over 3 months. For the past couple of months I have been waking up early in the mornings about 3:00 am with my heart racing and experiencing indigestion or heartburn, and sweating. I feel terrible when I wake up and feel as if I can't catch my breath. Last night it happened and I got up and took a Zantac and w/in 30 minutes I was fine. For the past week I have been experiencing bouts of using the bathroom about 3 times a day and then go a few days and not do anything. One of those days I did experience diarrhea. My stomache has been feeling crampy, bloated, gy, nauseaus, and I have not been running any fever. I've noticed soft drinks make me more gy than usual. I went to the Dr. about it and they took bloodwork and put me on antibiotics. The bloodwork was fine. Does anyone have any idea what could be going on? My mom said something about colitis. The waking up in the morning really scares me b/c I'm scared of having a heart attack I feel like my heart is about to jump out of my chest. I can also say that my nerves have been getting to me which probably doesn't help. The doc doesn't think my problems are from my surgery.