When I get more money I will try to see a Derm. I don't think my insurance covers it.
Yeah my clothing is rubbing all over. I remember back in the day when I wore baggy clothes and wide leg jeans, I never had body acne - just facial. Now my clothes are tighter and my face is clear and my back is a mess. I already wear XXL. Going any bigger would look ridiculous LOL.
I think it is cotton. It says cotton but I don't know if the dye in the clothes is doing something. I shower when I get back from the gym. I don't like showering in the gym itself. All those guys make me scared haha.
I stopped using fabric softner long ago. All my clothes are all stiff now haha.
Yeah I take tons of stuff for bodybuilding. But changing that is not an option. I don't feel I should have this stuff just because I am a bodybuilder.

Getting the lesions tested by a derm might help you refine a treatment plan for your skin. Its hard to come up with a way to treat it if you don't know what it is. Body acne, bacterial folliculitis, and fungal folliculitis all have different treatment options - so it would be good to know what you are dealing with.
You are probably having a harder time clearing your back because of the friction of your clothing rubbing on it - its one of the reasons its harder to clear body breakouts than facial. Also, the skin on your body is thicker and harder for products to penetrate.
Do you wear cotton clothing when you work out? Wearing something that breathes, and making sure you shower and change clothes as soon as possible after working out is important. Keeping your skin dry is really important - especially for a folliculitis problem. You might try using Gold Bond Powder on your skin - especially at times when your skin is sweating. It smells a bit medicinal, but it keeps your skin dry and also has some antifungal properties.
Do you use any fabric softener on your clothes, towels or bedding? If you do, that could be contributing to the problem. You want to use a fragrance free laundry detergent (like Cheer Free, All Free, etc.) and no liquid fabric softener or dryer sheets.
One other thought - since you have started working out a lot, have you added any body building supplements, protein shakes, etc.? Those can sometimes worsen breakouts.