Thanks for writing your query.
It will be helpful if you please mention whether you are also having some cold
also alongwith. If your Chest X-Ray and CT are normal, it might be a possibility that during coghing, some small blood vessels get ruptured and result in coughing of blood. Taking antihistamines like Fenofexadine
120 mg once a day may be helpful in controlling your cough and blood mixed expectorant.
It will be advisable that you should get yourself examined and take medication under medical supervision only.
I hope this is helpful to you.