Hello and welcome.
As per the given history,it appears your son has temporary Bruxism
It is very much normal at this age.There is continuous irritation in childs mouth due to erupting new teeth.
Thus they take up to such habits like grinding the teeth.
Its nice that you are well aware and keeping a good track on his activities.slowly the child will leave this habit.In case if you find this, continues even after the age of three then you must see Paedodontist(child specialist)in this regard.
Regarding rise in temperature,you can visit your dentist
once.Even mild rise in temperature is normal during teething
,but its better to see your dentist once for clinical evaluation.