Does this hot weather cause upset tums???

[Ihatefishing]

Both my son and his friend - both 2.5years have had upset tummies since Monday. They are not unwell with it and are drinking ok and eating although appetites are lower than normal.

Sorry if TMI but nappies are revolting, bit like teething.

Could the warm weather upset them as it all started when it got hot?

I will take him to the doctor if it doesn't clear up in 7 days.

Any thoughts?

My DS 5 years had runny tummy last wednesday.Sent back from school.He got better 2nd day.I am not really sure what is the cause.His peers where absent for 2 days,so may be..........