Unfortunately, while his tummy is now back to normal, his barking habit seems well established. He has his own internal alarm clock which goes off about half an hour before you want to rise, and he barks. He even does this on the weekend when you want to sleep in. This is becoming a real issue now, as it seems a lifetime since you had a decent slow start in the morning, and you're accumulating a sleep debt, which is making you grumpy.
If only there was something you could do about his early morning barking...
There is no magic involved in breaking this habit. Success depends on not responding to the barking and only rewarding silence. However, this pitches you against a dog's natural instincts to bark louder and for longer, when ignored. The first hurdle is to be aware this 'extinction burst' behavior is normal and to be expected, so that you can stick with the plan and see things through.
You will mainly need: