Gass! Please help! Ulcer formed inside?

I have gas type or maybe hunger type feeling in my upper abdomen, you can say in middle of end of rib and belly button... it feels like gnawing there, no pain, but gassy feeling. My stool is normal, but yellow in colour and probably i need to go twice a day to get fully clear... i have done LFT it was completely normal, but why this gas is not going? I have done a course of rifaximin given by doctor as well as taking pan 40.. no pain just gassy feeling always, my farts are smelly too sometimes, and also this gas feeling usually subsides after i eat something. And also sometimes there will be a gugugud bubbling sound and this gas will go away.. i dont eat any junk food or spicy food, nor m i on any medications. Why is it happening? And my stool is yellowish since weeks, by the gastro doctor said its normal only... Please help, is this gastritis or any ulcer formed inside? I am yet to do usg. I ewt fibrous food and drink enough water too.