If alcohol is not your particular problem, the Nyquil could give you some relief. Many years ago, before
I was in AA,
I blew three years of sobriety beginning
with Nyquil, which
I think was more potent in those days.
I'm a runner, so I get plenty of exercise, and try to rest and eat well, and I've escaped having a cold for nearly two years (knock wood), but I get paranoid when I'm around runny-nosed little kids or sitting next to people with a cough, and I wash my hands a lot.