This is most likely due to APD - acid peptic disorder or 'gas'. Acid peptic disorders can be of different types,in your case Acid reflux is most likely. This can cause loss of appetite with nausea.
Other causes of such loss of appetite can be stress, anxiety, chronic conditions like liver, kidney, etc. But diseases are unlikely for you. In your case acid peptic disorder along with stress are likely to be the cause of your symptoms.
For now, I would advise you to take the following steps taking this to be APD:
There are several OTC medicines which are generally safe which you can use for this. I would suggest Alka Seltzer two-three teaspoonfuls thrice daily. You should also take Cap. Prilosec 20 mg(OTC) once daily early in the morning. If you have any OTC anti acid medicines like Prilosec, etc you should take one now. You can also get it from the pharmacy if it is accessible. If you cannot get your hands on one right away, then have a glass of cold milk or ice cream. But get these from the pharmacy tomorrow.
Some other natural steps that you should take for control of these symptoms are:
*Cut down on alcohol and smoking
*have small frequent meals
*cut down on fried foods
*take sips of cold water or milk from time to time
These steps will give you relief. But do go to the doctor in the morning.
However, if it persists you need to show your doctor. You may need a thorough checkup by your doctor. But dont worry, these steps should be enough.
Also try to control your anxiety and stress, dont obsess about this.
Hope I have been able to clarify the situation for you and helped in resolving your query.
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Thank you and I wish you the best of health - stay safe!
Dr. P. Jyoti