Suggest Remedy For White Mucus In Throat

I use to smoke meth for a few months, and stopped a few months ago. I have white mucus build up in my throat and I think possibly my lungs from when I use to smoke it. It has caused breathing problems currently, shortness of breath, and heaviness/dull pain in my chest. I try to cough up as much of it as I can, and also gargle with warm water with salt added to it. I can clearly see it on the wall of my throat, rarely does it actually separate from the wall of my throat into my mouth to be spat out. I would like to know what other things I could do to help get rid of all of this buildup?