What is this stomach (and back) pain? Could diet help?

Hi,
I’m 25 Female with ongoing stomach and back pain.
The pain is reoccurring. I feel like right below my breast bone in my upper abdomen center. Sometimes it radiates down to the center of my abdomen and I almost always have middle back pain with it. Eating doesn’t particularly make it worse but once in a while I feel it after I eat and it doesn’t matter what I am eating. I’ve tried to cut meat or dairy for a little bit but still had the pain. I go on walks around the neighborhood for exercise about 5-6 days a week and I’ve noticed the pain starts around the time I start walking. Massaging and pressing down under my breast bone on my stomach helps with the pain. And I have no accompanying diarrhea or constipation. I do like to snack occasionally but I try to eat 1 full meal a day and I’ve been portioning my food and following my calorie intake. I do eat spicy food and sugar but I’ve been cutting it out and the pain still occurs.

It’s been difficult to make an appointment as I work 2 jobs and there aren’t many appointments available soon enough, what could this potentially be and should I try any lifestyle or diet changes?