4yr old cough, diarrhoea for 1 week, now high temp

[PJ67]

My 4 yr old had a couple of nights last week when he had a croup type cough when in his bed and has been left with a bit of a cough. He's also had loose stools for almost a week but has been fine in himself and eating and drinking. Today he's quite lethargic and has a bit of a temperature. I'm wondering why the high temp wouldn't have come first or at the same time as the cough started. Is it likely to all be related or not?
Thanks

I'm sure I don't need to tell you to keep a very close eye on this! The cough, loose stools, temperature etc. may be all unrelated, but a symptom that his immune system is at a low ebb and taking a hit.
If he's eating and especially drinking well, it's probably nothing to worry about and he will get better in his own time. If not, or he gets worse, or even if you just have a 'feeling' that he's not right get him to the GP ASAP!