By your letter,i came to know that you had viral infection and Pleurisy.So,it is clear that it has affected respiratory tract
You were on Antibiotics.It may cause Gastritis
which may lead to Nausea and sometimes vomiting.You didnt mention the other drugs that you are taking along with antibiotics.Whether you are taking Anti inflammatory drugs or Coticosteroids etc?They also cause Nausea and Vomiting.
One Possibility regarding Vomiting black substance can be altered blood which may be due to Gastritis/Stomach ulcer
Please consult your Doctor and get Upper GI endoscopy
done to confirm the diagnosis.
All the best