Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain as you are suffering from flu and on blowing the nose a ball of white stuff came out of nose with some blood in it seems to be thickened ball of mucous that gets accumulated in the nostrils and sinuses due to infection and at times it comes out during blowing of the nose.. Feeling dizzy after blowing nose is commonly seen during vigorous blowing of the nose and the cause can be due to sudden pressure changes inside the ears and movement of hair cells present in ears.. It is generally short lived and resolves soon.. You do not need an x ray of chest or anything else as of now as there does not seems anything serious.. As of now you can take decongestants like Pseudoephadrine [Sudafed], mucolytics like Ambroxol, do steam inhalations and use a humidifier in your room.. You can also use saline nasal irrigations to loosen the mucous and ease in its drainage.. In case if still you do not get relieve or the dizziness does not subside consult an ENT expert and get evaluated.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.