This is weird can anyone help?

I dont know what is wrong with me, i dont have a cold, no sore throat or runny nose. All i keep doing is coughing up flem and i feel like something is stuck in the back of my throat. I dont know what is wrong i will be fine for one minute then the next im coughing up flem If someone could help me that would be nice. & please no sarcasm or any sexual slurs im being totally serious.