Funky smell at nape of neck

I’m a white girl with fairly thick 2b hair. I decided to go no poo because my hair is super long (down past my butt) and I hated having it wet for pretty much an entire day every time I washed it. I exercise daily, and after I exercise I spritz my roots with diluted witch hazel, skritch my scalp, comb my hair out, and then do 100 strokes with a boar bristle brush. I’m overall satisfied with my hair texture. However, I’m starting to notice some serious funk in the hair at the nape of my neck, especially when it’s been hot for a few days. It’s somewhere between musty wet laundry and unwashed baseball cap. I suspect sweat and not getting dry is the culprit, but given that I exercise in the mornings (yes it has to be in the mornings) and go to work right after (my hair HAS to be braided or in a bun for work) I’m not sure what to do.

I water wash it maybe once a month. When I do I notice some decrease to the odor, but only till the next time or two that I get sweaty. Does anyone have suggestion for stuff I can spray on that won’t make me greasier but will cover up the smell? Other suggestions? I don’t want to wash it more often, because that is a royal pain in the butt and if I can’t wash it less often I might as well be using shampoo.