Hello ma'am
I share your concern
Bloating, loss of appetite and nauseous feeling might be related to number of conditions like
Acid peptic disease due to stomach hyperacidity
Liver or
gall bladder disease like gall stone
Indigestion
For all this complaints I would advise you to take antiacidity medicines like
pantoprazole or ranitidine group of drugs with antacids for 3 to 5 days if it doesn't subside than you need to see a physician.
As far as spotting in between periods at your age is a matter of concern, so I would advise you to consult a gynaecologist as per your convenience, for a pap smear, ultrasound pelvis and blood investigation like blood for
hemoglobin, CBC, Liver function test, blood sugar and hormonal assessment if need be.
Meanwhile have lots of fresh fruits and vegetables in your diet, avoid spicy and junk food,
you should take calcium and
multivitamin supplements.
Hope this answers your question, please feel free to ask for further assistance, I will happily answer you.
Best wishes