It's just sectarian clashes. Regardless of what religion you are, both Buddhists and Muslims are fleeing en masse to their respective neighbors to escape violence perpetuated on them by both sides.
Rohingya Muslims fleeing to Bangladesh due to military crack down, and Buddhist's fleeing east due to terror attacks committed by Rohingya militants. This is only going to get worse in the coming months.
Also why are you guys arguing about whether or not someone is following true to their religion? Religion is a purely subjective concept, and to judge people based on whether they follow the rules of their faith is handicapped (judge people by their actions committed). History has taught us that many religions have changed and evolved around what we deem acceptable.