can be related to loss of smell and if using regular medicine can impact the taste buds and in particular salt and oomani . I am asthmatic and the steroids and the sprays I have taken have impacted severely on my ability to taste in particular salt and a lot of food to me is quite tasteless . Also could be post nasal drip and gingivitis of issues with dental health .I would chat to an ENT or immunologist and or dental surgeon