Toddler tiredness

[PontypandyPioneer]

My just turned two year old has been constantly tired and out of sorts for about a month.

He's waking early shouting and angry, if I leave him he gets louder and bangs his head against the side of his cot and bangs his feet against the sides which makes him cry louder.
He's so tired during the day - he's barely moved from my side on the sofa since 6.30 this morning.

He naps for about an hour - recently not so much of a struggle to get him to sleep as usual so I know he's not well as I've had a battle for 2 years!
He had a really late nap a few days ago - 4pm! - which would have usually meant he would've gone to sleep at about 9 but he went at his usual time.

He's very clingy and cuddly - again this makes me think he's not well as he's not usually like this.

He climbed into his buggy this morning, told me to pull the hood over and just lay there for half an hour - no sleep though.

I took him to GP last week who sent him to hospital for a blood test and urine test. All came back normal. We're just waiting on one more result coming back. They say it's probably viral but a month seems like a long time for him to be unwell.

I just feel awful that I don't know what's wrong with him! He's usually on the go all day long and usually I can't get him to sit still or even stay in the house.

Any ideas? I don't suppose back molars would do this?

Sorry for the long post, wasn't supposed to be!