For past few years/for all my life I have found that I realize I have cold only when I wake up (in the morning time). It comes all of sudden. I never successfully pinned down what caused it. I usually blame the things that I ate in my dinner. I am again in standard cycle. I woke up and discovered my throat hurts a bit. Now, I know I would wake up tomorrow finding that it hurts more .... And, I always start wearing lots of warm clothes once it starts... sometimes I get out of it before it gets serious and once a year it wins.