Thanks for the prompt reply.
You've solved the problem by answering the questions, congratulations.
On the labia minora there are glands called Bartholin glands and also sebaceous glands.
These glands function to discharge secretions that keep the area moist and helps reduce friction during sexual intercourse.
Sometimes, these bartholin glands or sebaceous glands become blocked and there secretions acculmulate inside, they form cysts or small pimples like acne and then gradually dry off or pop. if they are small they can be left alone.
Only sometimes, they get infected and form an abscess, the patient experience extreme tenderness over them and they cause a great deal of discomfort. There is fever also. If an abscess forms formal antibiotic therapy and an incision and drainage by the surgeon is warranted.
In your case the pimples were due to your body's predisposition to them and also because you've been using a pad to help with your stress incontinence.
In my opinion you should keep your genital area as dry and clean as possible. Use pads with good absorpative abilities and keep changing them frequently.
You can use powders available in the pharmacies to keep the area dry also.
Hope I helped.