if it's a cold, it's viral and you just have to wait it out. you can't really "force" a virus out of the body. you have to wait for the body to build up an immunity to it.
sore throats can be caused by a bacterial infection, so that's a little different. TTO can be very potent, so i would be hesitant to try it. it would have to be VERY diluted. my parents used to have me gargle with a salt water solution for about 30 seconds. the salt can kill the bacteria too.
to soothe a sore throat, i sip hot water with lemon and honey. it just feels good. :D
for congestion at night, you can look at these small, plug-in vaporizers. they release menthol, camphor, etc. into the air and it opens up the air passages for breathing. it doesn't speed any healing, but it makes sleep easier. better rest does help the body heal.
plenty of fluids.
colds just take time.