Bad shed...which is strange

So my snake is shedding. It has been two weeks and the skin is finally coming off his body now with some patch of dead skin on his head and neck still.
This is weird because humidity is @ 75%

how do you check the humidity? a digital or analog one? analog one are usually not accurate.

you want use a pillow case, soak it in water, then squeeze it out, and put the snake in there for 10-15mins. then try rubbing the stuck shed.

If there is still some stuck, on his next blue phase, spray the enclosure to really2 bump up the humidity.

digital

Does your snake have anything in its enclosure that it can rub up against? This might help it to get its skin off.
Next blue phase spray your snake directly with warm water every day as EdShal mentioned. That's what I do and I get perfect sheds more often than not.