have lost appetite for food and having loose...

What is the cause of your symptoms ?
Well, there are many diseases the maigh be behind your symptoms such as Diabetes mellitis, anemia, H.pylori, vitamin D deficiency and others
How to treat your problem ?
Well, first of all you need to see a doctor in odrder to determine what kind of medical issue do you have and then the treatment will be accordigly. It's advised to get enough ammount of sleeping and rest, start a healthy diet rich in vitamins and minerals, drink a plenty of water in average of 2-3 liter per day. Try to avoid spicy food, alcohol intake, to quit smoking and to avoid stress and anxiety. For vitamin D defeciency, you can take Vit. D tab 50000 IU one tab per week for 6-12 weeks. For anemia, you will get benifet from taking iron tabs pr vitamin B-12 tabs.
Ho to get diagosed ?
Firstly, you should undergo a physical examination by doctor. Secondly, it's quite pbvious that we need to run some tests such as completet blood count will be ordered to check the hemoglobin level. Blood sugar to exclude diabetes. Measuring Vitamin D level in the blood. Stool analysis and urea breath test for H.pylori
Advice
You should follow the previous advices and follow up with you health provider