Hi, and thank you for coming to JustAnswer.com with your question.
It seems that you only typed part of what you were planning to. Can you finish it please?
Do I have a virus or chest infection
Both can cause the symptoms you are describing.
Do you have a fever?
Are you having trouble breathing?
Do you have a cough? If yes for how long?
Feel a bit breathless
No cough, symptoms only started today
If you are feeling breathless then you really should go to A&E and be checked out. There are many things that can cause difficulty with breathing, some are very serious.
Coughing up dark sputum can be from your lungs, but can also be from your stomach.
The breathlessness is the most concerning of your symptoms.
I hope you feel much better very soon!!