Maybe go for waxing? Razor is known to trigger folliculitis and dark spots. I had lot of that ( on my armpits and on the bikini area) when i was still using razors. It went away when i switched to wax.
And for the bumps and dark spots, an AHA lotion like Glytone or Amlactin can help.
use salicylic acid, it’s good for razor bumps and ingrown hairs, I use cerave SA, bar soap (for me the bar soap is better and last longer than the body wash verison) and/or you can get their SA lotion or cream