Mono doesn't get worse as one gets older. The severity depends on a variety of factors. For example, a hemotologist who was testing me for a familial genetic blood disorder (I was negative) told me when I was 35 that I'd had mono at some time in my life. I told him that I was never diagnosed with it, and he said that it could have been so mild that I simply felt 'unwell' for a few days. Then people can have a severe response, as you did. Your son may be simply having a milder response.
Good food and hydration are essential, and since his appetite is decreased by the illness, I would prepare foods he craves as much as possible.
He should recover fine without any need for acupuncture.
Thanks Emmie, that makes sense.