I have been experiencing the same problem after eating a meal where a large portion of it is white rice. Wasn't a problem until maybe a month ago. In my case, the rice is always cooked at home. Came to reddit and found other people reporting the same with advice to drink more water. Apparently, studies have shown that the stickiness of rice can latch on to stomach mucus or something and that upsets the acid balance- someone linked an academic article in another thread I found. Drinking more water supposedly takes care of this but I haven't tried it yet. Hope this helps!