Welcome to HCM!
I have read your query and there are some important points: nausea, 
severe dizziness, loss of appetite and 
weight loss, and you have to go to the toilet when ever you eat something ( I think that what you meant, but it is not written clearly). 
If I had been treating you, I would ask you to get some test done to make the picture clear-  most importantly you should get: blood counts, sugar, liver and kidney function test,  
lipid profile, and thyroid. Symptoms of sever dizziness points towards a possible neurological cause, so, getting an X Ray neck and may be if possible, get MRI brain.
I can understand that it looks like a whole lot of test have been asked but trust me they are just routine tests, only MRI will be costly.
once done, according to the test the treatment will move. For the time been, you may get relief from antacid, like 
Omeprazole 20 mg twice a day, half hour before meals, along with 
ondansetron to prevent nausea and 
gastritis. this will help you in eating and subsequently weight and health will improve. 
even if you can not eat much, ,continue with liquids to prevent 
dehydration. Diizness can be controlled for some time with tab. stemetil, as when required, upto two times a day.
One thing which is not clear from the question , is the sequence of appearance of your symptoms, it can just be a case of severe gastritis which had now lead to so much weakness that you have developed dizziness. In such cases, I have found good response with a course of antibiotics  and antacids as mentioned before.
 Also, the duration of your problem is two weeks, which means the cause is acute and should be well treatable. 
please do not loose Hope, you meet the doctor and get the tests done. 
Hope the answer helps  you
Feel free to ask more queries.
Dr. Manisha Gopal