This sounds extremely likely that you are describing recurrent herpes lesions- They recur at varying rates- in some people a couple times a year, in some people monthly and in some never. The location being on the thigh or abdomen or buttock is certainly consistent with herpes, and the description of multiple small 'blisters" grouped together is quite characteristic.
This is most certainly not a parasite.
Of course to be absolutely positive, a doctor would need to take a culture or sample of the lesions while they are active. But merely based on your description, I would be pretty confident in my diagnosis.
I would suggest describing it exactly as you have here to your doctor ( or seeing an infectious diseases specialist). They could also check for antibodies to herpes- by a blood test.
This is an important diagnosis to make, as there are antiviral medications that you can take, both to treat an episode, and to prevent outbreaks, if needed. Plus, once someone is infected with HSV, they always are, and you can spread the virus, even when you do not have an active outbreak.
Always ask if you need clarification/more information.
POSITIVE feedback & a BONUS are warmly appreciated.
Please note that answers are for information only, do not take the place of an IN PERSON assessment by your doctor,
and does not establish a patient-physician relationship.