Well, I'm not sure I can help. I thought I had an ulcer for two years but it turned out to be heartburn. You may have an ulcer or heartburn. The only way to really tell is to have a gastro doc give you an upper GI scope...this is where he puts a tube down your throat and looks in your stomach. There is a breath test for H. pylori also. I had it done and I didn't have an ulcer but the doc said it was heartburn.
If you have an ulcer, black tarry stools could be an indication of some bleeding somewhere. If you're breastfeeding, you're probably not taking alot of aspirin which is a no no for ulcers. Also, coffee, tea, sodas, and alcohol are no nos.
Some things you could try to see if your symptoms get better are DGL licorice...it is soothing to the stomach and is a natural antacid...it's not expensive..you can get it online at Puritan's Pride for about $12 a bottle. Take a couple before each meal. Danie has put out some threads on this site and she says it helped cure her GERD problems. Make sure it's DGL and not just plain licorice because the plain can cause high blood pressure. L-glutamine is an amino acid that helps heal ulcers. I don't know anything about mastic gum. Drinking lots of water will dilute the acids also.
If you have heartburn, the DGL will also help plus eating a more alkaline diet rather than too many acid producing foods will help also. DAnie has put out some threads on this site about the alkaline diet. It is basically alot of fruits (not citrus) and vegetables with very little grains or white flour products. Meats are also very acid producing. YOu can get protein from almonds and tofu.
One thing that you should really look at is the fact that you just had a baby and that can produce alot of stress, plus it sounds like you may some money issues also. Many of your symptoms could be stress induced especially stomach problems are the number one target for stress problems. Look at the Riverrotter thread and it talks alot of the mindbody connection to control pain symptoms. You really need to reduce the stress because it can cause many of your symptoms. I know that it can be hard, but find some quiet time to yourself (maybe during babies nap time) and get in touch with your inner feelings and try to confront any old issues where you might have repressed anger and sadness that is still harbored in your unconscious mind. These issues can cause the brain to produce pain symptoms in your body. John Sarno's book (Healing Back Pain) has helped alot of people with this. It's about healing back pain but his techniques work for any pain, and even heartburn and ulcers. I picked it up at the library. I'm reading his third book right now and I think there's something to it.
That being said, if your symptoms persist, you really need to see a gastro doc and have it checked out. At least to eliminate what you don't have. He'll probably tell you that you don't have any problems and then you'll know its stress related.
I hope you can find relief soon... you have your hands full with that new baby. Good luck.