Is it normal to have rough circular shapes on the arms when starting a fever?

My dad's been having these intermittent fevers for a few days now and when his temperature starts going up, these rough circles appear on his arms.

Has anyone seen or heard of anything like that before?

So you have a background on the situation, they've done quite a few blood tests that turned out normal, checked his heart and lungs and have yet to find an explanation to his condition.

The doctor doesn't seem to think it's a severe condition but is keeping him at the hospital until his condition gets back to normal or they at least find what's going on.