You need to get yourself evaluated by a pulmonologist/ chest physician. Investigations required are atleast chest xray, Serum IgE levels and pulmonary function test. The blood can be from your mouth/ due to a dental cause. Please get evaluated by a dentist
also (Since the bleeding is only at the time of brushing). If blood is noticed at other time i.e. either prior to or after brushing then there is a possibility of it being from throat or lower down and chances of secondary infection will be increased then. Based on your evaluation your treatment needs to be titrated.
Dr. Gyanshankar Mishra
MBBS MD DNB