Uncomfortable spots on bum

[Jojojeba]

For the past year I have been getting breakouts of spots on my buttocks and it's really bothering me. They are just like pimples except I'm not prone to acne anywhere else... they get red and sometimes sore. Sometimes bigger ones become whiteheads, but most are small and red and come and go. Over the past 12 months I've tried so many things: I've tried exfoliating, antiseptic wash, salycilic pads and ointments... I've tried heat pads, sudocrem, natural soaps, tea tree oil, olive oil (which improved the skin generally but hasn't got rid of the spots)... I don't workout so am not sitting around in sweaty gym gear as many people assume I must be... I do wear wear skinny jeans frequently and am sitting down a lot for work but seems an odd thing to suddenly flare up. Could it be a dietary issue or a skin infection or something? Anyone else had this?