Is it possible to have 3 Bartholin's cysts at once? 2 pea-sized lumps have gone down either side of labia minora, now a 3rd one, mostly red, no abscess.

Yes. It's unusual for that many to arise however it's certainly possible. Make sure that you're not shaving in that area or doing anything to cause skin abrasions in the area that can make these worse. Hot compresses can help to alleviate discomfort. If they get bigger and redder then you may need in office treatment with an i;d/catheter placement/marsupialization/excision.