Yellow diarrhoea, constant stomach and lower back pain, fever, fatigue. This is two weeks post gastro. What could it be?
Go back to doctor. Am assuming you underwent a gastroscopic procedure. In which case this has either not solved the primary problem or has somehow created a new one and the doctor who performed the procedure needs to reassess you.
I have had severe lower back pain, diarrhoea, tissue pain, poor sleep and tiredness. Also poor appetite and weightloss. Is it IBS and gibromyslgia?
Not yet. Must 1st rule out causes such as ibd, infectious, malignancy before even thinking of ibs and fb.
23f constant headache x2 weeks with no relief, nausea, fatigue, occasional dizziness, low back pain with some very mild low abdominal cramping/pain?
More information. You need to provide more information for any reasonable answer to your question. At any rate a complex problem like you describe can not be handled on line. I advise you to see a neurologist after an initial internal medicean examination.