Sounds like a cold/chest infection. There is a lot of it about.
I would actually be quite concerned about a temp of 39.9. I think that when you get above 40 you run the risk of other complications such as fitting. I would have rung NHS directat the time TBH - but as long as you can control it now it is less of a concern.
Keep an eye on the cough. If he seems to be struggling/labouring his breathing I would also contact NHS direct/walking centre etc.