Hi,Dear,
Thanks for the  query to My HCM Clinic.
I studied your query  in details and understood your health concerns.
-Treatment Advise and Cause of your lump in the inner thigh-
a-In -my opinion-it is Chronic furucullitis-which is recurring.The pus that came after pressing suggests that 
abscess was present inside without much of the pain and soreness to him.
b-Treatment I advise-is as follows-
i-AS its long standing lump -?Chronic 
furuncle with abscess I would advise -
FBS and PPS to rule out the 
diabetes in him-as a cause of it.
ii-The Chronic inadequately drained abscess needs further incision and proper 
drainage.
iii-Antibiotic Cover with Tb 
NSAID for 5 days would resolve the issue forever.
Consult your ER Surgeon for this.
This advise would help you to plan treatment with your doctor.
Hope this resolves your query.
Wellcome for further query in this regard. 
Have a Good Day...!!
With Regards