Nursing strike Please help me

All is in the title my 12 weeks and 2 days won't nurse he refuses to eat from my breast he is exclusively breastfed . He screams when my nipple goes near his mouth he refuses to put it in his mouth and I am scared. His last feed wahs 4hours and 40 minutes ago. How long can he go without breastfeeding ? I am terrified his blood sugar will drop or something? What can I do ? please help me. Update : I want to thank everyone for their advice you were lifesavers. I tried a few of your tricks and guess what !! They worked. I am currently breastfeeding him while walking around and when he is sleepy or just woken up from nap he is less likely to scream his head off. So thank you so much for your help, praying this nursing strike ends soon.