We have a water softener/ double cartridge whole house filtration system with sulfur smelling brown tinted water and tons of black sediment?

well our fridge has a filter and I installed a filter on the sink worked great for a year even though I burn through filters in 3 months instead of 6..well lately even with newer filters in fridge flushed of carbon the black sediments getting through.. im getting very annoyed and was told my wells fine and water softeners fine and that my sediment makes no sense we have flex piping and one small section of copper in this house... cant afford a plumber atm so looking for someones professional opinion or someone who has had this with their own home before and what the outcome was