Is this a virus you are familiar with?

[WeAreStars]

About a week ago my 2 year old had a temperature of 39 degrees for a day and was very weak and tired, barely any appetite, since then she's had no fever but has continued to very tired, grumpy and her appetite is reduced but she has no other symptoms at all. Her GP says it's a virus but I'm continuing to worry and question this as I've never known a virus that just causes tiredness and reduced appetite and no other symptoms. Is this something anyone else has come across?

[Sweetpotatoaddict]

I feel like since having children we've discovered a whole host of new viruses never previously encountered. Generally most things eventually prove themselves to be viral, also I find that my 2 year old despite chattering freely can't really articulate what they feel wrong. So I know he wouldn't be able to tell me about aching limbs/ headache/ dizziness/ sore throat etc.
I find my 2 yr old goes through phases of no appetite and tiredness for no apparent reason. And we often have a few days of grumpiness which I put down to development. I don't mean to be dismissive just through experience I've worried about ds and then a few days later thought, 'ah well back to normal must be a virus'.
Hope she's back to her usual self soon and if not I wouldn't hesitate to take her back to the gp.