Do i have PBS?

Hi I'm a 13 years old boy and for the past few months I've been having general problems gastrointestinally. It started out with me just having a lack of appetite. Then school started and my appetite came back. Then after a while i started to have a lot of gas and i would belch a lot after eating. I went to see a doctor during the summer about it and he pressed on my stomach and told me to try and change my diet for a while. Nothing really changed. But anyway now I have had some abdominal pain. No specific area just all around. And when i do its pretty brief. I have also had some pain up my anus. My bowel movements seem normal, maybe just a little harder than normal but theres no bleeding as far as i can see. I'm kind of worried and I'm kind of embarrassed to talk to my family about it. Some thoughts on this would be appreciated.