What Causes White Mucus Expectorant Along With Nausea?

My spitting had started around thanksgiving i am not sure what it is but i am always spitting and it is getting worse day after day. The stuff i am spitting out is white&clear looking & i be feeling nauseous & sick my mom says its coming from my rotten teeth because of infection but i never had this before. Can you please tell me what you think it could be ? And thank you ! I would greatly appreciate it