Hi, Welcome to Health care magic forum.
I think that the boil on the hand is the main cause of all these things.
Due to the boil,there will be fever, head ache, weakness, etc.The boil may need to be incised and drained.
The stomach pain, nausea,
diarrhea, loss of appetite, abnormal heart beats, short ness of breath, etc may be due to the
indigestion of the fever, or the infection of the intestine.
I advise you to consult a physician for diagnosis and treatment.
I usually prescribe to my patient with such symptoms
ofloxacin,
ranitidine,
domperidone,
paracetamol, lactic acid bacilli and
loperamide .
Wishing for a quick and complete recovery. Thank you.