Do illnesses make spd temporarily worse?

Hi, my son (4) hasn't been officially diagnosed as yet but is presenting with symptoms of spd and his physiotherapist believes he has sp issues. Anyway, he has had a several bouts of illness, mostly recurring sore throats and very bad colds, over this past year and as well as being generally out of sorts, his symptoms seem to be worse, his concentration and attention span gets shorter and whilst he will eat if you feed him, he won't feed himself and pretty much would ignore food, even food he likes, all day if I let him. His co-ordination also disimproves but I'd expect that seeing as the sicknesses are ENT related.