Only wash your hair every other day. Use dry shampoo when it really needs freshened up - Lush & batiste both do powder-based ones which are less of an irritant than aerosols. Also, try changing up your shampoo. A few months back I used Schwarzkopf Gliss for a few weeks and it did not play nicely with my scalp, even though I've used it before with no problem. My favourite shampoo is Rehab from lush, which leaves my hair feeling cleaner than I thought possible, and is kind to your scalp. Head & Shoulders Original is my fav cheap alternative.
But seriously, just try to detox your hair and avoid using any products as much as possible. Try and keep it to the bare minimum of shampoo and conditioner every other day. It might look hella greasy at first, but it will get used to being washed every other day. At one point I could get away with washing my hair once every 3 days, even with regular sweaty workouts, and it looked great! Even if you can't commit to training your scalp, give it a rest whenever possible. Not going outside for 3 days? Don't wash your hair! I get that it can feel so gross not washing properly after a workout, but try just soaking your hair while in the shower and not shampooing it. Feels better than nothing at all.