It may be his time of month, be supportive and don't react to his taunting.
This will only cause more problems.
The more understanding you show now the easier it will be in the long run, some men once a month and generally on the full moon will suffer from what is only a natural bodily function.
Once it is over things will go back to normal.
Try not to be insensitive as his hormone levels will be through the roof.
And also it's clear to me a few men replying to this have clearly broken what is called " the bro code" this is disappointing to see.
Fraternising with the enemy unbelievable you must all know about filthy girl germs surely didn't you learn anything in grade 1.
If those early fundamental principals were not ingrained in you at that age than its clear the next 11 years of schooling were clearly a wasted time