Am guessing just the flu. but very aching upper legs. back of head. lower back. no energy. runny nose. has not got any better for 3 days.

Symptomatic Rx: Sounds like a cold. No cure for that but it is about rest, fluids, and time and of course managing the symptoms. Consider decongestants and antihistamines. Cough syrups and drops may be of benefit. If you are a smoker now would be a good time to stop. Ibuprofen and paracetamol will help with the aches.

Flu : Sounds like flu which is a viral infection. Treatment is symptomatic only . Try paracetamol or brufen for aches and fever provided you are not allergic to them . Can try nasal decongestants . Honey , lemon and ginger drinks , and soups would help you feel bit better and most important is resting .

'Flu-like': Yes, your symptoms sound 'flu-like'. It could also be another virus which isn't actually influenza. Either way it doesn't make a difference to how you treat it. Rest, fluids, over the counter pain relief for aches and headaches. The symptoms are worst in the first 3 days and then resolve over 7-10 days (2weeks at most). You are most infectious to others in the first 5 days.