Thanks for your query
i can feel your concerns
Because of your disease i-e autoimmune neutrpenia,you are very much prone to infection.
The function of neutrophils is to fight against forgein bacteria .Because of neutropenia
your neutrophils cannot protect your body against bacteria.
now you have got an abscess
on your thigh.it is basically a collection of pus and bacteria.
i advise you to take painkiller like brufen
after consulting your doctor
wishing you good health