7 year old with sudden hives

[NK5BM3]

Hi there
I'm wondering if someone can take a look at this and tell me it's nothing? Ds suddenly presented with these hives. The picture is that of his knee. There are now on his face (cheeks) as well as his hands.

There's not been a change of food or washing powder. He says it's slightly itchy.

I'm panicking as he's had a history of systemic juvenile idiopathic arthritis and those rashes look v similar to the ones he had 3 years ago. But of course then, he also had a fever and joint pain. This time he's fine, no fever, no joint pain. He's still active, playing tennis and swimming. And going to school. He's currently in remission and not on any medication like methotrexate etc.

He's also been having fainting spells every few weeks. The last few have been every month or so. With no apparent reason. He says 'it's stuffy'

Thanks in advance.

Is there any chance he had a flea in his trousers? My flea bits look a bit like that. Are they itchy?

Sorry just seen they are in hands/face too

Bites of some description.

Thanks for the quick responses. They disappear and then reappear if that makes sense. So tomorrow, they would subside, and then come up again, possibly in a different place. This was what happened 3 years ago. I'm trying not to panic that it's not his arthritis flaring up!

Hopeful Bump for the morning crowd...