Suggest Remedy For Coughing Yellow Mucus

hello
i had a few questions concerning coughing up orange and yellow mucus, i am rarely sick and usually if i get sick it doesn't last for more than a few days, i am not running a fever, nor do i feel sick. however i have been having a sore throat lately, also the occasional headache with some post nasal drip, now i have been dealing with this for about a week now and woke up this morning and coughed up orange/yellow mucus, this is the first tme i have ever seen this before and i was wondering what this was? is this serious should i go to the doctor? i have been having terrible post nasal drip and having to blow my nose quite constantly, especially during the night when i try to sleep. can anyone tell me whats wrong with me? i have been told this is a sinus infection, but the way im hacking almost every minute or so, it is starting to seem more serous