Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain a boil on the back of upper thigh along with fever can be due to hair
follicle infection also known as Folliculitis while it can also be due to infection in the oil glands..
When the infection reaches the blood the body tries to wall off the infection and there is rise in body temperature..
I would suggest you to consult a General Physician or a
General Surgeon and get evaluated and a clinical evaluation is generally sufficient while a blood test can help in further confirmation..
He can advise you to take a course of antibiotics like
Ciprofloxacin or
Metronidazole, anti-inflammatory painkiller like Aleve or Motrin..
You can also be advised to apply steroid and antiseptic cream over the boil..
You can also do warm compresses over the boil..
In case if it does not heal in a week to ten days, he can do
incision and drainage..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.