Thank you for the information,
There can be a few possibilities.
Cysts like an epidermoid or sebaceous cyst is a possibility which is benign in nature.
Other possibilities can be wart but you have got tested for std.
Growth or cancer needs to be ruled out but they should increase in size over 12 months.
Other possibilities are Fordyce spots, pearly papules which usually do not need any treatment.
I feel you need an examination of the lumps by doctor.
Doctor can then decide about its plan of treatment.
I hope this information helps.
I will be happy to assist, if you need any clarification.
Please feel free for any follow up query.