Recurring virus - 3 years now....

[sparksey]

I don't know if anybody can help or has experienced this but any words of advice would be great.
My DS is 5 and this is the 3rd year running he has had a "virus". It always starts september time and lasts through till late spring early summer.
The symptons start with a sore tummy which leads to diarrhoea then a day later sore throat,enlarged glands coughing and slight temperature with the tummy ache and then high temperature and fever like.
This starts in sept lasting a good 3-4 days and recurres approx every 3-4 weeks. As the weather gets warmer it starts to die out and he gets fewer bouts of it and it lasts about 2 days.
We have a new GP who we started to see as this was dying out in may/june. He tested for urine infection that came back fine and I will be going back tomorrow to see him as DS has just started to come down with it again.
Can anyone shed light on this or what I should be asking the GP to test for because DS is really getting fed up with it now and he feels so grotty and tired when he gets it.
I'm presuming it's not contagious as DD who is 3 hasn't caught it once.

I have no medical knowledge, but could it be an allergy?

Seems unusual that he gets it same time every year and that noone else catches it.

do you use anythign different in the winter that you dont in the summer? eg tumble dryer fresheners? scented candles?

do you have a plant which flowers/pollinates around this time, either in or out of the house?

do you bring a pet eg a rabbit etc indoors?

Might be barking up the wrong tree entirely, but allergies make me quite unwell and can upset my tummy, i often get a fever with them, but realise that this is most likely a different virus which I have caught due to my immune system being low whilst my body deals with my allergy.

Allergies also make you VERY grotty and tired.