Baby suddenly heat sensitive

[Quadrilingual]

My baby (8 mo) has started to dislike the bath recently and started to cry. We think he is finding it too hot but it's always been 36-37 degrees that he has his bath water. He has also started getting clusters of red spots which appear and disappear on his body and we think it's heat rash. He's happy and fine all day and spots don't seem to bother him. Any idea why he is suddenly so sensitive to heat?

Do you put anything else in the water? Might be a reaction. Otherwise put in more water or less to keep him comfy. Can get toys to entertain at this stage.

We use Johnson's baby wash which he has used since birth but maybe it no longer suits him so we will try shorter bubble bath. We give him toys too. I guess we'll know once we change bubble bath if it's that or water temp or food. Thanks for the suggestions!