My kid has yellowish pee like this, orange stain in his diaper (urate crystals, I guess), and he cries for no apparent reason but when I checked, he's crying while he pees. He has no fever as of now and as jolly and lively as ever. Do you think it's UTI?

Urate crystals are signs of concentrated pee but it doesn't necessarily mean your kid has UTI. Yes, urate crystal is a sign but look for other symptoms to. It can also be dehydration. Signs of dehydration include dry lips, lethargy, less to no pee, among others.