Hi everyone

I'm normally a relatively health person but this year I've been struck down
twice by 'flu-type' viruses for periods of over 2 months.
I'm not completely laid out, but am not well enough to go to the gym or walk
over a mile without feeling exhausted.
Does anyone have an idea why this could be or could suggest a course of
treatment (other than taking paracetamol? )
Thanks for any advice.