It has to be what you're eating, unless you already had a chronic case of pyrosis/GERD before going vegan. Does it flare up worse in the evenings, when lying down or sleeping? That is GERD if it does.
Try avoiding acidic foods and beverages. Bananas are a good non-acidic fruit to satiate your fruit desires. Just do a Google search for what's high or low in acidity.
I also would consider consulting a doctor. It is recommended to see a doctor before making such a lifestyle change, anyways.
The bottom line is meat is highly acidic. So regardless, you are still better off without adding meat back into your diet. I would also evaluate what's different in your diet, aside from not eating meat. What have you added since going vegan?
Perhaps keeping a daily journal of every last thing that goes in your stomach would give you a better idea. Use a process of elimination, if necessary.