P.M.
If the infection reached his inner ear, his sense of balance could be out of whack, and he may not be able to stay vertical.
This can be extremely distressing – I had to be hospitalized for a whole day once to get extreme balance and nausea issues under control. I couldn't even open my eyes because the room was whirling so fast. Then it took half a year to get back to normal, with the world no longer spinning unexpectedly out from underneath me.
I'm glad your friend is taking her son to the doctor. He may really need it. If not inner ear/balance issues, then possibly some secondary infection that is also troubling.