Feeling nausea and fullness after eating a little,, and also abdominal pain ihave to take rennie ( a tablet that i chew ) to feel better what ?

Many possibilities: There are many possibilities, and talking to a doctor is the best way to get an evaluation. Relief from Rennie (short acting antacid) makes it possible you have gastritis/GERD/ulcer disease, and it may be worth trying a longer acting antacid pill such as Pepcid(famotidine 40mg twice daily) or Prilosec (omeprazole 20 mg once/day) for two weeks. If symptoms persist, do talk to your doctor!