What Causes Sore Throat And Excessive Saliva While Lying Down?

Hello there, I have had a sore throat for last few days, my boyfriend just had a cold so think I have caught it from him. It s not been a really horrid cold so far, but a bit odd, I haven t had anywhere near as much blowing of the nose due to mucus, only a little. My throat was really sore the first day, then faded, then is a bit scratchy in the evening times. When I have been going to bed the last few nights I haven t been able to sleep as I have to keep swallowing due to excess saliva, have never had this before but is making me wonder if this is a cold or not something else? Any help would be appreciated, many thanks, Siobhan.