What happena if when I breathe I get a pain in my neck?

Depends. Is the 'pain' actually pain, or soreness, irritation, etc? Is it in your 'neck', or your throat? Does it happen with each breath? Normal breathing, or labored breathing? Lots more information necessary for sound answers. Go see your dentist, or ent...Also your primary care physician would all be first choices.
Pain with breathing. This is not typical and a more thorough history and physical exam including an chest x ray should be obtained first. It most likely is a pinched nerve. However, a lung injury (pneumothorax) or mass could also be responsible.

Related Questions

I have had neck pain for a couple of months now and occasionally I get a stabbing ache in my neck on the right hand side when I breathe in, help?

Hard to say. Severe headache and neck pain could be due to many life threatening and some minor. Without the correct history and physical it would be unwise to recommend more than seeing your doctor in person. If pain is this severe perhaps visiting the local emergency room would help. Cheers. Read more...