while it is not normal to lose 13 pounds in 1 week it;s not going to kill you or anything - it is most likely mostly water weight. From reading your post you said you are little overweight which may be greatly contributing to your problem. Try to eat healthy and lose the weight. I see you eat a lot of oatmeal, fruits white rice etc - it's fine to eat those but they are loaded with carbs and will not really help you lose weight. What you need to eat is a balanced diet that includes low carb, low fat and high protein. If you will have 1/2 cup of rice (make it a brown rice) have baked or grilled chicken breast with it - if you eat oatmeal, eat it with milk and maybe some egg whites - fruits with protein shakes or greek yogurt or cottage cheese etc. And drink a lot of water. Also you will need to excersise daily - it helps with overall health and helps to move food along. And not 15 minutes 3 times a day - you need more like intense 45 minute workouts consisting of weight training and cardio 4-5 times a week so you can lose the unhealthy weight.
As far as bloating, you should schedule appointment with gastro doctor to do endoscopy and see what's going on - just because you are bloated and feel full doesn't mean you have cancer - you may have gastritis or esophagitis and medication should take care of it in few weeks.
I hope this helps and you feel better soon.